RU2409440C1 - Method of rotary burnishing of billets - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, in particular to rotary burnishing of billets. Billet is rotated, while tool made up of spinning rolls, are fed in lengthwise and crosswise directions. Unit of spinning rolls consists of two rolls fitted on one axle and separated by spacing ring. Said rolls feature profile consisting of three sections, i.e. starting, squeezing, burnishing and gauging cylinder. Note here that said starting section is made on one roll rigidly fitted on the axle with forced rotation. Said roll needle surface is made from metal wire frieze bunches with preset front angle. Second roll running free in axle bearings has spinning section arranged at preset angle and burnishing section with preset angle separated by gauging cylinder that represents a sine tape.

EFFECT: expanded process performances, higher quality and efficiency.

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Description

The invention relates to the processing of metals by pressure, in particular to methods and devices for rotational smoothing and pressure processing.

A known method of pressure treatment with a pressure roller, the cross section of which in the plane passing through the axis of rotation parallel to the forming mandrel, is limited by a flat end mating transition section with a radius of 0.5 ... 0.8 diameter of the pressure roller, the working section outlined along the radius with the peripheral part made in the form of a cylindrical surface with a generatrix parallel to the axis of the roller and smoothly conjugated with the working surface in cross section of the largest diameter of the pressure roller [1].

The known method has a significant drawback: the selected angle in the range of 6 ... 12 °, non-observance of which leads to a reduction in productivity and tool life due to the rapid wear of the working surface, limited by the radius, while to obtain high quality it is necessary to create large working forces, and this requires the use of rollers with a large profile radius, which negatively affects the overall dimensions and is not always feasible.

There is a method of pressing processing carried out by a roller, the cross section of which in a plane passing through the axis of rotation is limited by the conjugate arcs of circles of different radii, and the ratio of the radii of the circles is selected in the range 13-15 [2].

The disadvantage of this method, implemented by a pressure roller, is the low roughness of the finish of the processed surface due to the small contact surface interacting with the part, which leads to low surface quality and requiring a large number of technological transitions, which dramatically reduces productivity. Another disadvantage is the difficulty of restoring the shape of the roller as a result of wear, since for this it is necessary to grind all external surfaces with a change in grinding radii to maintain a mate of radii. At the same time, adjustments are required in the technological modes.

A known method is implemented by a pressure roller with a double-sided cone, in which the angles φ and φ ₁ are selected in the range from 30 to 35 °, and the mating radius of the conical surfaces take from 6 to 8 sheet thicknesses, i.e. from 6 to 32 mm [3].

The known method is good for rotational smoothing of shells with a convex-concave surface, but does not ensure the achievement of surface roughness, eliminating the need for surface refinement by grinding.

Known methods of rotational smoothing, carried out by pressure rollers, the nature of the course of the processing process which depends on the radius of rounding and the width of the girdle [4]. However, a disadvantage of the known methods is the difficulty of restoring the shape of the rollers as a result of wear, since for this it is necessary to grind all external surfaces with a change in the grinding radii to maintain the mating radii. At the same time, adjustments are required in the technological modes. In addition, the disadvantage is the small contact surface interacting with the part, which does not provide a high roughness of the finish of the processed surface, which results in low surface quality and requires a large number of technological transitions, which sharply reduces productivity.

The objective of the invention is the expansion of technological capabilities, improving the quality and productivity during processing, improving the conditions of deformation and the flow of metal, as well as reducing the likelihood of expansion, expansion of metal and the occurrence of scoring on the treated surface, reducing the likelihood of sagging in front of the tool when processing thin-walled workpieces from durable materials.

The problem is solved by the proposed method of rotational smoothing of workpieces, including the message of forced rotational movement of the workpiece and longitudinal and transverse feed to the tool, which is used as a block of pressure rollers, consisting of two rollers separated by a spacer ring on one axis, one of which is rigidly set on the axis with the possibility of forced rotation, has a lead-in section with a rake angle of φ = 20 ° ... 30 ° and a needle-shaped peripheral surface of bundles of pile of metal wire, a second roller freely seated on bearings on the axis has a crimp portion at an angle φ ₂ = 30 ° ... 40 ° and ironed portion to the rear angle φ ₁ = 35 ° ... 45 °, separated by a caliber belt formed in the form of a sinusoidal tape.

The essence of the proposed method is illustrated by drawings.

Figure 1 shows a block of pressure rollers that implement the proposed method for rotational smoothing of both thin-walled and thick-walled parts, a partial longitudinal section; figure 2 is a view along B on the front end in figure 1; figure 3 - element In figure 1; figure 4 is a section GG in figure 3; figure 5 is a section DD in figure 3.

The tool block consists of two rollers 1 and 2, mounted on one axis, and serves to improve the conditions of deformation of the workpieces. The workpiece, for example, worn on a mandrel (not shown), is given a rotational movement, and the needle roll 1 is forced rotational movement V _AND , while the pressure roller 2 receives rotation from the workpiece due to friction forces. In addition, a longitudinal S _PR feed is reported to the block.

The performance of rotary smoothing and the quality of the surfaces of parts largely depend on the shape and geometric parameters of the pressure rollers.

The tool block consists of two rollers 1 and 2, mounted on one axis 3. The rollers are separated by a distance ring 4. The block has a complex profile and consists of three sections - inlet 5, crimp 6, ironing 7 and gauge belt 8.

The approach section 5 is made on one roller 1, mounted on the axis 3 rigidly with the help of a key 9, fixed on the axis by a nut 10 and having a forced rotation with a speed of V _AND from an individual engine (not shown). The peripheral surface of the lead-in section 5 is made of needle wire from tufts of pile made of metal wire with a rake angle φ = 20 ° ... 30 °. The tufts on the pile wire portion 5 are fixed by known methods and create favorable conditions for the formation by introducing the needles into the treatment surface and a driving force at a rotation speed V _{and the} workpiece, eliminating slippage and reducing the likelihood of sagging before crimping and ironed. For the introduction of needles into the treated surface before processing, the tool block is fed in the transverse direction to create an interference fit within 0.5 ... 1.0 mm.

The second roller 2 is freely mounted on the roller bearings 11 on the axis 3, secured by a cover 12 and has a working surface consisting of a crimp section 6 made with a rake angle φ ₂ = 30 ° ... 40 ° to the axis of rotation and a smoothing section 7 with a trailing angle φ ₁ = 35 ° ... 45 °. Roller 2 rotates independently on bearings, which makes it possible to reduce the difference in speeds at the points of contact of the tool with the workpiece, improve the flow conditions of the metal and reduce the likelihood of galling on the work surface. The rake angle φ ₂ is the angle of entry of the metal into the deformation zone and the smaller it is, the less stress in the deformation zone, the more stable the process of rotational smoothing.

The block allows you to deform, for example, tubular workpieces to various lengths in any section with preliminary introduction into the metal. The crimping part 6, which is the inlet, of the roller 2 has an angle φ ₂ = 30 ° ... 40 °, which helps to reduce the influx, and also affects the stability of the process and the distribution of forces between the longitudinal and transverse components. A smaller angle φ _{2 is} taken when machining aluminum, copper and low carbon steel, a larger angle φ ₂ is used when machining high-strength steel and titanium, since the deformation forces decrease with an increase in the angle φ ₂ .

When φ ₂ <20 °, the possibility of sagging in front of the roller increases, which is undesirable.

Between the crimp section 6, made at an angle φ ₂ to the axis of rotation, and the ironing section 7 with a rear angle φ ₁ is a calibrating girdle 8, made in the form of a sinusoidal tape. The belt 8 prevents the appearance of sagging in front of the roller 2, which is very likely when processing thick-walled workpieces. The calibrating girdle, as a rule, is taken with a width of k = 1.5 ... 3 mm, where k is the width of the girdle of known designs of pressure rollers. Since the longitudinal feed, determined by the formula S _PR = (0.2 ... 0.3) k, depends on the width of the belt, they tend to increase the width of the belt, however, with wider belts k, the deformation forces increase significantly and the quality of the machined surface decreases.

In order to increase productivity and improve the quality of the processed surface during deformation by the proposed method, the calibrating girdle 8 is made in the form of a sinusoidal tape, characterized by the magnitudes of the amplitude K and step A (see Fig.3-5). This design allows for the same width of the calibrating girdle (k = K ₁ ) and without increasing the deformation force, to increase the longitudinal feed S _{PR by} n = (K / K ₁ ) times and to improve the quality of the processed surface.

The radius of the working edge R, which is assumed to be approximately equal to the thickness of the deformable workpiece, has the same effect.

When applying S _PR = (0.2 ... 0.3) K, the roughness of the treated surface is achieved from Ra = 40 μm to Ra = 1.25 μm. The radiuses of conjugation of the sinusoidal girdle K with the working faces take within 1 ... 3 mm. In the manufacture of interfaces between the calibrating girdle 8 and surfaces 6 and 7, the front φ ₂ and rear φ ₁ angles slightly decrease and take values φ ₂ ′ and φ ₁ ′, respectively, however, these changes do not significantly affect the operation of the unit (see Fig. 4 , 5).

The proposed method, implemented by a block of pressure rollers, is used on powerful pressing machines operating by the method of reverse rotational smoothing of thick-walled workpieces [3, 4]. The diameters of the rollers are taken from design considerations. With an increase in the diameter of the roller, deforming forces and bending moments acting on the support of the machine increase. It is necessary to strive to use rollers of the same diameter for each machine. This is especially important for CNC machines.

Work on the deformation of the proposed method is carried out with minimal rigidity of the inlet needle part. As a pile, a steel spring wire is used, for example, with a diameter of 0.5 ... 1.0 mm from steel 65G. Use the needle part with the ratio h / I, where h is the length of the pile over the hub of the roller; I - the smallest radius of inertia of the cross section of the wire elements within 50 ... 100, and the coefficient K _{p the} density of the wire pile in the range of 0.6 ... 0.8; the tightness was - i = 0.7 ... 1.5 mm.

Modes of operation of the needle part: peripheral speed V _And taken equal to the speed of the workpiece. As a result, the roughness by one class is improved, the force of pressing the acrylic on the workpiece surface is 200 ... 300 N per 10 mm of the width of the working surface of the needle part.

For processing with a needle block, it is necessary to observe the condition: p / σ _in = 1.5 ... 2.0, where p is the pressure during needle formation, MPa; σ _in - the tensile strength of the material of the workpiece, MPa.

The choice of the appropriate pressure p depends on the physicomechanical properties of the material of the wire pile, on the rigidity and density of the latter, as well as on the interference fit i.

Since the needle roller wears out on the outer diameter, it is desirable for the purpose of restoration that the tufts of the pile radially extend and grind on the outer diameter after each dressing.

The surface microrelief formed as a result of smoothing is determined by the following main factors: kinematics of the process (the direction of mutual movement of the tool and the workpiece being machined); initial roughness; the shape and size of the initial part and the smoothing tool; the depth of penetration of the tool into the work surface; feed rate; plastic flow of metal, causing the appearance of secondary roughness; roughness of the working part of the tool; the value of the elastic recovery of the surface after smoothing; vibrations of the technological system machine-tool-tool-tool-workpiece, as well as the magnitude of the tightness of the needle tool.

When ironing parts made of steel, brass and aluminum alloys, good results are obtained by using industrial oil I-20A or sulfofresol as a lubricant.

Using the proposed method allows to expand the technological capabilities of rotational smoothing due to the combination with a needle block and a sinusoidal calibrating girdle, to increase the quality and productivity of processing, to improve the conditions of deformation and flow of metal, to reduce the likelihood of expansion, expansion of metal and the occurrence of scoring on the treated surface, as well as to predict roughness and quality the processed surface.

Information sources

1. USSR Copyright Certificate, No. 1620182, MKI B21D 22/14.

2. Copyright certificate of the USSR, No. 845980, MKI 3 B21D 22/18.

3. The grave NI Rotational extraction of shell parts on machines. M .: Engineering, 1983, S.144-145, Fig. 9.2.

4. Mogilny N.I. Rotational extraction of shell parts on machines. M .: Engineering, 1983, p. 147, Fig. 9.6.

Claims (1)

A method of rotational smoothing of workpieces, including a message of forced rotational movement of the workpiece and longitudinal and transverse feed to the tool, which is used as a block of pressure rollers, consisting of two rollers seated between themselves by a spacer ring, one of which is rigidly mounted on the axis forced rotation, has a lead-in section with a rake angle φ = 20 ° ... 30 ° and a needle-shaped peripheral surface from tufts of pile made of metal wire, Torah roller seated freely on bearings on the axis, has a crimp portion at an angle φ ₂ = 30 ° ... 40 ° and ironed portion to the rear angle φ ₁ = 35 ° ... 45 °, separated by a caliber belt formed as a sinusoidal strip.

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