RU2332293C1 - Method of processing spherical surfaces by surface plastic deformation - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention pertains to the technology of machine building, and particularly for processing work pieces by plastic deformation. The rotating work piece is acted upon by the deforming instrument. The deforming instrument is in form of at least three bushes, pressed in a holder, with an inner working surface of: at least one first bush, at least one middle bush and the last bush. The holder is moved in a direction perpendicular to the longitudinal axis of the work piece. The indicated bushes have a longitudinal groove for free passage of the neck of the work piece. The inner working surface of the first and middle bushes is splined. The splined surface of the middle bush is displaced in the peripheral direction on one spline relative the splined surface of the first bush. The inner working surface of the last bush is smooth and cylindrical, and the spherical surface of the work piece is calibrated on it. As a result, the technological capabilities are increased, as well as the output, quality and accuracy of processing.

EFFECT: high quality and accuracy of processing spherical surfaces of work pieces by surface plastic deformation.

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Description

The invention relates to mechanical engineering technology, in particular to methods and devices for hardening, calibrating and deforming drawing of metal spherical surfaces of parts, for example automobile ball fingers, from steel and alloys by surface plastic deformation (PPD).

A known method and device for processing surface plastic deformation of workpieces having a spherical surface and a neck associated with it, comprising exposing a workpiece with a deforming tool to a workpiece rotating relative to its longitudinal axis to perform interference fit [Patent RU 2188115 C1, V24V 39/04, 08/27/2002 ].

The method and device is characterized by limited capabilities, low efficiency and productivity, a small depth of the hardened layer and a low degree of hardening of the treated surface, complexity, high energy consumption and metal consumption of the structure, as well as overall dimensions.

A known method and tool for processing incomplete spherical surfaces of parts of the PPD, in which the workpiece and the deforming tool are notified of rotational motion, and the deforming tool is informed of rotation in a circle lying in a plane offset from the center of the processed spherical surface, while the angular velocity of the deforming tool is associated with the angular speed of the workpiece by the ratio ω _in >> ω _d , in addition, a mathematical relationship between the force loading and rolling force [1].

The method and tool are characterized by low efficiency, high energy consumption, a small depth of the hardened layer and a small degree of hardening of the treated surface, while the applied non-self-aligning tool does not allow to obtain a high-quality processed surface.

There is a known method and a double-row impact tool realizing it for processing external cylindrical surfaces, in which the first row of rollers is mounted on an elastic "floating" mandrel which is mounted in the radial direction, and the second row of rollers is mounted on a rigid mandrel [2].

The method and tool are characterized by limited capabilities and are used only for processing external cylindrical surfaces, low efficiency and productivity, a small depth of the hardened layer and a low degree of hardening of the processed surface, complexity, high energy and metal consumption of the structure, as well as overall dimensions.

The objective of the invention is to increase the productivity, quality and accuracy of processing the spherical surface of the workpiece, as well as expanding the technological capabilities of PPD through the use of the original design of the deforming tool, which allows you to control the depth of the hardened layer, the degree of hardening and the microrelief of the processed spherical surface.

The problem is solved using the proposed method for surface plastic deformation processing of workpieces having a spherical surface and a neck associated with it, including the action of a deforming tool on a workpiece rotating relative to its longitudinal axis to perform interference fit, using a deforming tool in the form of a pressed tool at least three bushings with an inner working surface: at least one first sleeve, at least one middle bushings and the last sleeve and tell the cartridge the feed movement in the direction perpendicular to the longitudinal axis of the workpiece, while these bushings have a longitudinal groove for free passage of the neck of the workpiece, the inner working surface of the first and middle bushings is made in the form of a spline surface with dimensions d _protr and d _VP , the spline surface of the middle sleeve is offset circumferentially by one slot relative to the spline surface of the first sleeve, the inner working surface of the last sleeve is made with a smooth cylinder Coy surface, which calibration is carried out in the spherical surface of the workpiece size d _sph, the diameters of the internal working surfaces of bushings determined from the following expressions:

d _protr = d _zag -2 · 0.8 · t; d _VP = d _zag ; d _sf = d _zag -2 · t,

where d _zag is the outer diameter of the spherical surface of the workpiece, mm; d _lug - the inner diameter of the bushings on the protrusions of the slots, mm d _VP - the inner diameter of the bushings along the slots of the slots, mm; t is the interference, mm; d _SF - the outer diameter of the spherical surface after processing, mm

The essence of the proposed method is illustrated by drawings.

Figure 1 shows a diagram of the surface plastic deformation (PPD) of the spherical surface of a spherical automobile finger, which shows the final position of the workpiece before leaving the tool contact zone; figure 2 is a top view of a in figure 1; figure 3 is a section bB in figure 1; figure 4 is a cross-section bb in figure 1; figure 5 is a cross section GG in figure 1; Fig.6 is a diagram of a divided plastic deformation of three bushings.

The proposed method is used for PPD and hardening of metal spherical surfaces, for example, in spherical automobile fingers 1 and other parts of steel and alloys. The method is implemented using the device 2 for installing, basing and securing the workpiece with the possibility of rotation relative to the longitudinal axis and the deforming tool 3.

The deforming tool 3 is a set of bushings pressed into the cartridge 4 mounted, for example, on a vertical broaching machine (not shown).

The cartridge 4 with a deforming tool 3, consisting of several working sleeves 5, 6 and 7, makes a feed movement S _CR in the direction perpendicular to the longitudinal axis of the workpiece 1, while the workpiece makes a rotational movement V _s relative to its longitudinal axis.

Deforming sleeves 5, 6, 7 in an amount of at least three have a longitudinal groove for free passage of the neck 8 of the workpiece, mating with a spherical surface 1. The inner surface of the holes of the sleeves 5, 6, 7 is working and has a shape depending on the purpose:

- the first contact with the workpiece sleeve 7 (or more sleeves) is used to pre-FPD and has a splined surface with dimensions d _Venue - internal diameter splined sleeves and the slot on the ledges d _sn - inner diameter of spline bushings depressions slot;

- the middle sleeve 6 in contact with the workpiece (or several bushings) also serves as a preliminary PPD and has a spline surface with the same dimensions d _protrusion and d _vp , but shifted in the circumferential direction relative to the first sleeve by one slot;

- the last sleeve 5, which ends the processing of the workpiece 1, serves for the final PPD and has a smooth cylindrical surface that calibrates the spherical surface of the workpiece in size d _sf .

The internal diameters of the spline holes of the bushings are determined by the formulas

d _VP = d _zag ; d _protr = d _zag -2 · 0.8 · t; d _sf = d _zag -2 · t,

where d _zag is the outer diameter of the spherical surface of the workpiece, mm;

d _lug - the inner diameter of the spline bushings on the protrusions of the slots, mm;

d _VP - the inner diameter of the spline bushings along the slots of the slots, mm;

t is the interference, mm;

d _SF - the final outer diameter of the spherical surface after processing, mm

The width of the slots on the bushings 6 and 7 is slightly larger than the width of the depressions and is taken equal to b _W = 1,1 · b _VP .

The bushings 5, 6, 7 are sequentially sealed in the cartridge 4, guaranteed against turning by press fit and setting the keys 9. From below (according to FIG. 1), the cartridge 4 is closed by a cover 10.

The main technological parameter of the PPD process is an interference fit t, which is provided by a divided plastic deformation scheme between, for example, three deforming bushings 5, 6, 7.

When passing the sleeve 7 from top to bottom (according to FIG. 1) and rotating the workpiece around its own longitudinal axis, traces of indenting the slots (pos. ₇ , Fig. 6) are formed over an area slightly more than half the entire surface of the sphere. The remaining part of the sphere is treated with slots of the next sleeve 6 (pos. T ₆ , Fig.6).

Thus, the preliminary PPD of the entire spherical surface is made sequentially by two bushings. With large diameters of the sphere, the preliminary PPD process of the entire spherical surface can be performed sequentially by several bushings. However, traces of successive processing by several bushings remain on the surface of the sphere. Therefore, a sleeve 5 is provided for the final PPD (pos. ₅ , Fig. 6), which is made with a smooth inner working surface having a final, final size d _sf .

The inner surface of the bushings has straight slots, as the most technologically advanced in the manufacture, for example, by pulling or chiseling, however, the slots can be made with screw.

The divided scheme of plastic deformation allows us to reduce forces in case of RPM and their effects on the rotation mechanism of the workpiece, which increases the life of the tool and equipment as a whole and positively affects accuracy and productivity.

For complete processing of the spherical surface, the workpiece at the moment of movement along the sleeve rotates with an overturn by 1.15 ... 1.25 turns relative to its own axis. Thus, when moving the cartridge over the entire total length of all bushings, the workpiece rotates by 3.5 ... 4 turns.

When processing with an interference fit of t up to 0.5 mm, shape deviations in the cross section (deviation from roundness) are reduced, size accuracy is increased by 30 ... 35%, and surface roughness parameters are reduced. With such interference, workpieces are also treated after heat treatment.

The total interference is limited by the ductility of the workpiece material. Billets made of brittle materials are processed with small tightnesses, since with high tightness it can break.

Processing with bushings provides optimal conditions for deformation - the tool has maximum dimensional stability.

The material of the bushings is VK8 hard alloy and other wear-resistant tool materials.

The radial runout of the working surface of the sleeve bore should not exceed 0.02 ... 0.05 mm.

When processing by the proposed method, a lubricant-cooling technological agent (COTS) is necessarily used, which prevents the sleeve from setting with the metal being treated. The absence of COTS leads to the rejection of workpieces and often to the destruction of the tool. For billets of carbon and low alloy steels are recommended: sulfofresol, MP-1, MP-2, emulsions. The same liquids should be used in the processing of blanks from non-ferrous metals (bronze, brass, aluminum alloys). For parts made of high alloy, heat-resistant and corrosion-resistant steels and alloys, the following SOTS should be used: АСМ-1, АСМ-4, АСМ-5, АСМ-6. When machining billets of hardened steels, ASF-3 grease is used.

The roughness of the surface treated by the proposed method depends on the initial roughness and the material of the workpiece, the processing mode used by the SOTS. The roughness of the treated surface does not depend on the processing speed (within the range of applied speeds). To obtain small values of the roughness parameters, it is advisable to pre-treat the outer spherical surface with a carbide tool, for example, a cutter having small angles in plan (φ = 30 ... 40 °), at cutting speeds that exclude the formation of growth. When processing the sphere after roughing and finishing turning (initial parameter Ra = 6.3 ... 1.6 μm), surfaces with Ra = 0.8 ... 0.1 μm are obtained if the workpiece material is steel; Ra = 0.4 ... 0.1 μm when processing billets of bronze and Ra = 1.6 ... 0.4 μm when processing billets of cast iron.

The surface roughness after plastic deformation by the proposed method will be the lower, the less the interference at which the processing of the sphere. So, when processing a workpiece made of steel 45 with an initial roughness of Ra = 4 ... 8 μm, we obtained the following roughness with interference on a deforming tool:

Preload t, mm 0.05 0.10 0.20 0.30 0.50 Parameter Ra, μm 0.06 0,07 0.4 1.3 3.0

Hardening of the metal is a consequence of the occurring deformations. The hardening, expressed by a change in hardness, decreases with the transition from the machined surface to the depth of the billet sphere. The thickness of the texture layer with increased hardness is greater, the greater the tightness and the less, the higher the initial hardness of the processed metal. The increase in hardness depends on the metal being processed and is 130 ... 250%.

The speed of the rotational movement of the workpiece V _{s is} assigned within 2 ... 25 m / min.

To achieve accuracy in 11 ... 13th qualifications, processing is carried out with great interference. To achieve accuracy in the 8 ... 11th qualifications, medium tightness (0.2 ... 0.5 mm) should be applied. To obtain accuracy according to the 5 ... 6th qualifications, preliminary precise machining is necessary, after which the deformation is carried out with small tightnesses (0.02 ... 0.2 mm). For the last group of workpieces, a scheme is advisable: deformation - cutting - thin deformation.

Example. We processed the PPD blank of the ball upper finger 2101-2904187, installed in a special electromechanical device on a vertical-broaching machine mod. 7B65, by the proposed method. The blank is made of steel 20X GOST 1050-74. Processed a sphere with a diameter of 32.7 ± 0.1; the initial roughness parameter Ra = 3.2 μm, achieved - Ra = 0.63; a deforming tool in the form of bushings made of VK8 hard alloy in the following modes: workpiece rotation speed V _s = 5 m / min (n _s = 50 min ^-1 ); the speed of the longitudinal feed of the deforming tool S _CR = 0.2 m / min; total tightness on diameter - 0.2 mm (0.1 mm per side); the depth of the layer of high hardness was 0.15 ... 0.20 mm; Sulfofresol (5% emulsion) served as the cutting fluid.

The required roughness and accuracy of the spherical surface was achieved with one pass in T _m = 0.1 min (against T _m ^bases = 2.75 min according to the basic version in the traditional ball rolling treatment at the Oryol steel mill OSPAZ). The control was carried out by an indicator bracket with an indicator ICh 10 B cells. 1 GOST 577-68 and on the profilometer mod. 283 type AII GOST 19300-86. In the processed batch (equal to 100 pieces), no defective parts were found. The deviation of the treated surface from sphericity was not more than 0.02 mm, which is acceptable TU.

The processing showed that the roughness parameter of the treated spherical surfaces decreased to Ra = 0.32 ... 0.63 μm with the initial value Ra = 3.2 ... 6.3 μm, the productivity increased by more than five times compared to running in. The energy intensity of the process decreased by 2.2 times.

The proposed method improves the productivity, quality and accuracy of processing the spherical surface of the workpiece, and also expands the technological capabilities of PPD through the use of the original design of the deforming tool and allows you to control the depth of the hardened layer, the degree of hardening and the microrelief of the processed spherical surface.

Information sources

1. RF patent 2031770, MKP ⁶ V24V 39/04, 39/00. A method of processing incomplete spherical surfaces of parts by surface deformation. Gavrilin A.M., Samoilov N.N. 5045958/27; 04/14/92; 03/27/95. Bull. No. 9.

2. Reference technologist-machine builder. In 2 vols. T.2 / Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed. reslave. and add. - M.: Mechanical Engineering, 1986. P.392, Fig.14b.

Claims (1)

A method of processing surface plastic deformation of workpieces having a spherical surface and a neck associated with it, comprising exposing the workpiece to a workpiece rotating with respect to its longitudinal axis by a deforming tool to perform an interference fit, characterized in that a deforming tool is used in the form of at least three bushings pressed into the cartridge with an inner working surface: at least one first sleeve, at least one middle sleeve and the last sleeve and inform patr Well feed motion in a direction perpendicular to the longitudinal axis of the workpiece, and wherein said sleeve has a longitudinal slot for the free passage of a neck of the preform, the inner working surface of the first and secondary sleeves is made as a splined surface with dimensions d _Venue and d _vp, slotted face of the middle sleeve is biased circumferential direction by one slot relative to the spline surface of the first sleeve, the inner working surface of the last sleeve is made with a smooth cylindrical surface, which carry out the libration of the spherical surface of the workpiece in size d _SF , the diameters of the inner working surfaces of the bushings are determined from the following expressions: d _protr = d _zag -2 × 0.8 × t, d _vp = d _zag , d _sf = d _zag -2 × t, where d _zag is the outer diameter of the spherical surface of the workpiece, mm; d _lug - the inner diameter of the bushings on the protrusions of the slots, mm d _VP - the inner diameter of the bushings along the slots of the slots, mm; t is the interference, mm; d _SF - the outer diameter of the spherical surface after processing, mm

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