RU2287426C1 - Method of static-pulse expanding - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: method comprises setting the device into the opening to be worked, setting the blank in rotation, feeding the device to the surface to be worked, and applying the static and pulse loading perpendicular to the surface to be worked. The device is made of mandrel with deforming tools, striker, and waveguide made of rods. The mandrel is provided with changeable deforming tools secured to the plungers that are arranged along the radius. The free ends of the plungers are in a contact with the conical surface of the waveguide. The striker and waveguide are mounted at the central longitudinal axis of the mandrel. The free end of the waveguide is provided with the cylindrical compression spring. The static load is generated with the use of a stack of plate springs mounted on the plungers.

EFFECT: expanded functional capabilities.

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Description

The invention relates to mechanical engineering technology, in particular to methods for hardening the treatment of internal surfaces of parts made of steels and alloys by surface plastic deformation with static-pulse loading of the tool.

A known method and device for the finishing and hardening of parts by rolling [1], in which the feed motion and the processing speed of the tool and the workpiece are contacted under normal static load applied to the surface normal to the work surface in the range of forces ensuring the achievement of a given roughness and periodic pulsed load, changing in the specified range from minimum to maximum value. In this case, the load ripple frequency is selected depending on the required hardening depth.

The method and device that implements it is characterized by limited capabilities, low efficiency, high energy intensity, insufficient depth of the hardened layer and insufficiently high degree of hardening of the treated surface.

A known method and device for static-pulse treatment by surface plastic deformation, carried out by a tool, to which a constant static load and a perpendicular pulse load, which is communicated by the striker and waveguide, and the shape, amplitude, effective duration and frequency of single force pulses are normally applied to the surface to be treated deformations are determined by the above formulas [2].

The known method and device are characterized by limited control capabilities in creating heterogeneous hardened layers and regular microrelief of the treated surface.

The objective of the invention is to expand the technological capabilities of static-pulse treatment by surface plastic deformation by controlling the depth of the hardened layer and the microrelief of the inner surface by using a tool of a special shape.

The problem is solved using the proposed method of static-pulse rolling, in which the device in the form of a mandrel, containing deforming tools, a striker and a waveguide made in the form of rods, is introduced into the machined hole, give a longitudinal feed, and the workpiece is rotated, and the mandrel has interchangeable deforming tools mounted on radially located plungers, the free ends of which are in contact with the conical surface of the waveguide, while the waveguide and the striker laid on the central longitudinal axis of the mandrel, in addition, using a package of Belleville springs mounted on the plungers normally to the work surface, apply a static load and periodic impulse load using a striker acting on the waveguide, while a helical cylindrical compression spring acts on the free end of the waveguide .

The essence of the method is illustrated by drawings.

Figure 1 presents the processing scheme for the proposed method of static-pulse rolling, longitudinal section; figure 2 is a cross section aa in figure 1; figure 3 is a General view of a device that implements the method; figure 4 is a view of B from the left in figure 3; 5 is a diagram of a method for introducing a device into a hole to be machined; figure 6 is a cross section bb in figure 2.

The proposed method is used for surface plastic deformation of the inner surfaces of the workpiece 1 using a constant static and periodic pulsed load on the tool, while the device that implements the method, in the form of a mandrel 2, containing deforming tools, a striker and a waveguide made in the form of rods, is introduced into the machined hole, give a longitudinal feed, and the workpiece - rotational movement.

The workpiece 1 receives a rotation V _s , and the device for rolling in the form of a mandrel 2 - the movement of the longitudinal feed S _CR along the axis of the workpiece. The deforming tools 3 are removable and fixed at the ends of the radially located plungers 4, in an amount accepted for structural reasons.

The free ends of the plungers 4 are in contact with the conical surface of the waveguide 5. The waveguide 5 and the strikers 6 are located on the central longitudinal axis of the mandrel 2. Packets of Belleville springs 7 are mounted on the plungers 4, due to which a static load is created, acting normally on the workpiece surface 1.

The choice of design and number of cup springs (GOST 3057-79) depends on the specific processing conditions and technical requirements for the surface to be treated.

A hydraulic pulse generator is used as a mechanism for impulse loading of instruments [3, 4]. The workpiece is informed of the rotational movement, and the device is provided with a longitudinal feed, they are brought into contact with the help of a split ring 8 (Fig. 5) with a conical inner surface, which allows plungers with tools to be separated to the longitudinal axis, which are divorced under the action of a packet of Belleville springs.

A periodic pulsed load P is applied to _them in the direction of longitudinal feed and, thanks to the clinoplunger mechanism consisting of plungers 4 and a conical waveguide 5, they are directed normal to the surface to be treated.

A periodic impulse load P _is carried out using a hammer 6, acting on the end of the waveguide 5, which radially spreads the plungers with the tool with their cone. In order to divert the waveguide after impact to its original position (according to Fig. 1, to the right), a helical compression spring 9 acts on the free end of the waveguide (GOST 13766-68).

As a result of the impact of the striker 6 at the end of the waveguide 5, shock and oppositely directed pulses of the same amplitude and duration arise in the striker and waveguide, each of which will affect the plungers, tools 3 and the treated surface with a cycle equal to double the duration of the pulses. Having reached the surface to be treated, the shock pulse is distributed on the passing and reflecting. The passing pulse forms the dynamic component of the strain force.

In modern mechanical engineering, dynamic surface-plastic deformation processes mainly use deforming tools having a spherical, disk or cylindrical shape, tools in the form of a disk roller of double curvature, tools in the form of a threaded roller for rolling a threaded surface, etc. Therefore, in the device, the deforming tools 3 are removable, fixed at the ends of the radially located plungers 4 (Fig.6). The ability to rationally use the energy of shock waves is determined by the size of the instrument.

The depth of the hardened layer processed by the proposed method reaches 1.5 ... 2.5 mm, which is significantly (3 ... 4 times) more than with traditional static hardening. The greatest degree of hardening is 15 ... 30%. As a result of static-pulse processing according to the proposed method, compared to traditional rolling, the effective depth of the layer, hardened by 20% or more, increases by 1.8 ... 2.7 times, and the depth of the layer hardened by 10% or more, 1.7 ... 2.2 times.

Example. To assess the quality parameters of the surface layer hardened by the proposed method, experimental studies of the processing of the liner using a special stand. The values of technological factors (impact frequency, tool radius, feed rate) were chosen in such a way as to ensure the multiplicity of impact on the elementary area of the treated surface in the range of 6 ... 10. A further increase in the multiplicity of the deforming effect leads to softening.

The value of the force of static preloading of the tool to the work surface was P _article ≥25 ... 40 kN; P _them = 255 ... 400 kN. Billets made of steel 40X; initial hardness of “raw” samples is HV 270 ... 280. The depth of the layer hardened by static-pulsed processing is 3 ... 4 times higher than with traditional rolling.

The hardened layer in the traditional static rolling is formed under long-term action of large static forces. According to the proposed method, a similar depth of the hardened layer is achieved as a result of a short-term impact on the deformation zone of a prolonged energy pulse. At close degrees of hardening of the surface layer, the magnitude of the static component of the load by the proposed method is much less.

Studies of the stress state of the hardened surface layer by static-pulse treatment showed that the maximum residual stresses are close to the surface, as when chasing, which is favorable for most of the interfaced parts of mechanisms and machines.

A comparison of the depth of the stressed and hardened layer, the stress gradient and the hardening gradient shows that the depth of the stressed layer is 1.1 ... 1.3 times greater than the depth of the riveted layer, which is consistent with the theory of surface - plastic deformation.

The maximum roughness value achieved during processing by the proposed method is R _a = 0.08 μm, a reduction of the initial roughness by a factor of 6 is possible.

Microvibrations in the process of static-pulse rolling favorably affect the working conditions of the tool. The imposition of a small amplitude oscillatory motion leads to a more uniform distribution of the load on the tool, causes additional cyclic movements of the contact surfaces of the tool and the workpiece, facilitates the formation of a hardened surface.

Fluctuations contribute to a better penetration of the cutting fluid (coolant) into the treatment area. When vibration is applied, the deforming surface of the tool periodically “rests”, which helps to increase its resistance.

Processing under vibration conditions dramatically increases the efficiency of the cooling, dispersing and plasticizing action of the coolant due to the facilitation of its access to the contact zone between the tool and the workpiece.

Sources of information taken into account:

1. A.S. USSR, 456719, MKI V 24 V 39/00. The method of finishing and hardening of parts by rolling, 1974.

2. RF patent 2098259, MKI ⁶ V 24 V 39/00. Lazutkin A.G., Kirichek A.V., Soloviev D.L. Method of static-pulse treatment by surface plastic deformation. No. 96110476/02, 05.23.96; 12/10/97. Bull. Number 34.

3. Kirichek A.V., Lazutkin A.G., Soloviev D.L. Static-pulse processing and equipment for its implementation // STIN, 1999, No. 6. - S.20-24.

4. RF patent 2090342. Lazutkin A.G., Kirichek A.V., Soloviev D.L. Water hammer device for processing parts by surface plastic deformation. 1997. Bull. Number 34.

Claims (1)

The method of static-pulse rolling, including the introduction of a device in the form of a mandrel with deforming tools and made in the form of striker and waveguide rods into the hole to be processed, communicating rotational motion to the workpiece and longitudinal feed to said device, characterized in that a waveguide with a conical surface and a mandrel with interchangeable deforming tools mounted on radially located plungers, the free ends of which are in contact with the conical surface in the waveguide, and the firing pin and waveguide are located on the central longitudinal axis of the mandrel, apply a static load normally to the surface to be treated using a packet of Belleville springs mounted on the plungers, and a periodic pulse load with the help of a firing pin acting on the waveguide, the free end of which is affected by a screw coil spring compression.

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