RU2376121C2 - Method and device to renew expansion-cam parts by plastic deformation - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building, namely to renewal of worn parts by plastic deformation and can be used at repair plants to renew expansion-cam-type parts along with increasing their fatigue strength in critical sections. Proposed device comprises bed accommodating split sections of die to form cavity there between to mate sizes of expansion cam head part, and top plate with punch holder fixed therein. Said punch holder houses two punches, their front surface facing that of renewed part and being equidistant to it. While rear surface, on the side of part that requires no deformation, is flat. In compliance with proposed method, part is preliminary heated to hot deformation temperature and renewed in aforesaid device.

EFFECT: expanded performances.

2 cl, 1 tbl, 7 dwg

Description

The invention relates to the field of restoring worn-out parts during operation by plastic deformation by introducing a specified configuration into a worn-out part of a tool and can be applied at repair enterprises engaged in the renovation of parts.

The closest in technical essence and the achieved result to the proposed device is a device for restoring both the outer and inner surfaces of the bushings. The device contains a base, a heating source, a matrix for placing the product and powder, a rotation unit and a forming element made of a composite of two coaxial hollow parts. The disadvantage of this device is its use only for hollow parts, as well as the lack of hardening of the part after restoration [1].

Another closest in technical essence is the method and device for the restoration of spherical elements of parts by the method of plastic deformation, which is intended for the restoration of spherical elements of parts. The device consists of a bed, a heating source, a detachable matrix for accommodating the part and the punch, and also contains a wedge for fixing the sections of the matrix from longitudinal movement, while the left section of the matrix is rigidly fixed to the bed, the matrix sections are made with a locking element with the possibility of formation between them in the assembled state of the cavity corresponding to the geometric dimensions of the heated ball element of the part. A method for restoring spherical elements of parts by plastic deformation, including preheating the part to hot deformation temperature and installing the part in a detachable matrix for subsequent distribution. The restoration of the spherical elements of the part is carried out using a stamp, and after plastic deformation it is subjected to mechanical and heat treatment [2].

The disadvantage of the analogue is the possibility of its use only for the restoration of axisymmetric, in particular spherical, elements of parts by plastic deformation. The objective of the invention is to expand the technological capabilities of the restoration of resource-intensive parts by plastic deformation on parts of a more complex configuration, as well as providing methods for selecting the optimal form of the punch, which provides the closest to the necessary distribution of metal flows. This task is achieved by the fact that the device for restoring the outer surfaces of the head of the parts of the type "expanding fist", containing a bed, a heating source, a detachable matrix for placing the part, a wedge for fixing the right section of the matrix from longitudinal movement (the left section of the matrix is rigidly fixed to the bed, sections of the matrix are made with a locking element with the possibility of the formation between them in the assembled state of the cavity corresponding to the geometric dimensions of the heated expandable element of the part) also contains two deforming elements, the shape of which is selected according to the following procedure.

In the process of studying the influence of various factors on the metal flow during piercing with punches of various shapes, several patterns were identified, the consequence of which are the following recommendations for constructing the shape of the punch in non-axisymmetric cases, which will provide the required directional movement of the metal masses in the direction of wear during recovery (Fig. 2 - here : 18 - the restored part, 19 - the restored surface of the part, 20 - the front surface of the punch, 21 - the rear surface of the punch, 22 - the end face of the punch):

1) the shape of the front surface of the punch (the surface of the punch facing the restored surface of the part) must be equidistant to the restored surface;

2) the shape of the back of the punch (from the side of the surface of the part that does not need to be deformed) should be flat;

3) the angle during the transition from the front surface of the punch to the back does not affect the shape change (metal outflow towards the corner is practically absent);

4) when choosing the shape of the end face of the punch, one should be guided by the data from the table and Fig. 7 (here: d is the diameter of the punch; hk = 0.25d; Hk = 0.5d), i.e. choose the shape and relative dimensions of the punch such that the maximum approximation of the shape change size of the part in the most characteristic part of the work surface, the plane perpendicular to it (work surface), to the value selected from the table;

5) it is necessary that the shape of the part obtained after flashing with the designed punch provide sufficient strength characteristics corresponding to the working conditions of the part;

6) the volume of the inserted punch should be greater than or equal to the sum of the volumes of wear of the part, the volume of flashing obtained during recovery and the volume of metal that is removed during subsequent processing.

The implementation scheme is shown in figure 5, which shows two punches of the same shape and the head parts "expanding fist", which must be restored. The scheme of the restored surfaces of the part is shown in Fig.6, where 19 are the surfaces to be restored, 26 are the surfaces that should not be deformed during the restoration process, 27 is the wear area.

The data given in the table (see Appendix) express relative shape change and to a small extent depend on the shape of the surface being restored. Explanations for the notation are given in figure 3, where: H is the height of the cylindrical sample; H 'is the height of the cylindrical sample after the introduction of the punch; D is the diameter of the cylindrical sample; dв, dcp, dн - respectively, the upper, middle and lower diameters of the sample after the introduction of the punch.

The annex “Research Protocol” provides the rationale for the data given in the table. The unit of measurement is a value equal to the measured size of the sample before implementation. Thus, the measured value characterizes the relative shape change of the sample, which does not depend on its initial shape.

In the method of restoration by the method of plastic deformation, the restoration of the expanding elements of the part is carried out using the device in figure 1 (here: 1 - bed; 2, 17 - detachable section of the matrix; 3 - bolts; 4 - punches; 5 - springs; 6 - punch holder; 7 - intermediate plate; 8 - upper plate; 9 - coupling bolts; 10 - shank; 11, 12 - stop bolts; 13 - wedge; 14 - puller; 15 - release springs; 16 - guides; 18 - restored part), and after plastic deformation of the item is subjected to mechanical and heat treatment.

The device for recovering expandable elements of parts by the method of plastic deformation contains a wedge for fixing the matrix sections from longitudinal movement, while the left section of the matrix is rigidly fixed to the bed, the matrix sections are made with a locking element with the possibility of forming a cavity between them in the assembled state corresponding to the geometric dimensions of the heated expanding element the details. The invention relates to devices for restoring the outer surface of the head part of parts of the type "expandable fist" (Fig. 5, in which 4 are inserted punches; 18 is a restored part and Fig. 6, in which 19 is a worn surface of the part (surface requiring restoration); 26 - the rear surface of the part (the surface does not require restoration); 27 - the restored volume) with a simultaneous increase in their fatigue strength in dangerous sections. The restoration of the part is carried out by introducing the specified configuration into the tool part and can be applied at repair enterprises engaged in the renovation of parts.

The proposed device consists of a housing 1 (Fig. 1), on which detachable sections of the matrix 2 and 17 are mounted. The right section of the matrix 17 is mounted on T-shaped rails 16. The sections of the matrix are made in such a way that the lateral movement of the sections relative to each other is fixed. The left section 2 is rigidly fixed to the frame 1 using bolts 3. A shank 10 and a punch holder 6 are mounted to the upper plate 8, in which the punches 4 and the wedge 13 are mounted, fixed to each other through the intermediate plate 7 by the tightening bolts 9. The design of the device allows it to be used during restoration various types of punches 4 (figure 1), which are presented in Fig.7.

The device works as follows.

The head of the restored part 18 is preheated in a non-oxidative heating unit (salt bath) to a hot deformation temperature (from 0.8 to 0.9 T _pl ) and is installed with a shank in the hole of the lower plate, which secures the part until the matrix sections are closed. When the press slide moves down, the right section of the matrix by means of the wedge 13 along the guides 16 moves to the working position. The geometrical dimensions of the wedge are selected in such a way that the created preload between the matrices ensures the exclusion of the possibility of their disclosure, thereby ensuring that the metal does not flow into the joint. The restored part 18 is clamped between the two sections of the matrix 2 and 17. The punches 4, penetrating into the part, due to plastic deformation of the metal, the parts fill the cavity of the matrix.

After the restoration process is carried out, the device is returned to its initial position by the presence of exhaust springs 5. The spring travel is limited by the stop bolts 12. During the movement of the top plate 8 upwards, the part is removed from the punch by means of the puller 14, and the wedge 13 also rises, allowing the right section of the matrix 17 due to return springs 15, acting through the thrust bolts 11, to return to its original position. After restoration, the part is removed with ticks.

In the assembled state, a cavity is formed between the matrices that corresponds to the geometric dimensions of the heated head of the expanding fist with an allowance for subsequent machining of the reconditioned part. The restoration of geometric dimensions is ensured by the targeted movement of the material of the part from non-working zones to the area of the worn surface due to the introduction of two punches of a given configuration.

The direction of the metal flow depends on the shape of the tool being introduced and the friction condition at the contact of the punch - the restored part - the forming matrix. To create anisotropic conditions of friction during plastic deformation (Fig. 4, where 18 is the restored part; 19 is the worn surface (the surface needs to be restored); 23 is the adhesion zone; 24 is the direction of metal flow when the punch is inserted, 25 is the slip zone) on the engraving matrices, adhesion zones 23 and slip zones 25 are created. A thin line shows the worn surface 19 of part 18. Due to the characteristic shape of the tool being introduced and the direction of flow of the metal 24, the part will take the necessary shape after restoration. For this, the surfaces of the matrices, where it is necessary to create adhesion zones, are processed by milling operations (Ra = 6.3 μm), and the slip zones are processed by grinding operations (Ra = 1.25 μm).

The proposed device and method allows to restore resource-worn parts such as expanding fist while increasing their fatigue strength.

Literature

1. Patent RU No. 2129941. "A method of restoring the sleeve of a plunger pair of a diesel engine high pressure fuel pump."

2. Patent RU No. 2238832. "Method and device for the restoration of spherical elements of parts by plastic deformation."

application

Research Protocol.

The experiment involved:

1. Ziganshin Ramil Fazylovich.

2. Pankratov Dmitry Leonidovich.

The conditions of the experiment:

1. The studies were carried out by numerical simulation in the QForm3D program (version 3.2)

2. The results of the study were saved in the form of a contour of the sample after implementation, in the form of tabular data (measurements were carried out in figure 1), as well as in the form of a * .qfm file

3. The boundary conditions for mathematical modeling:

a) the material of the part is steel 45,

b) the heating temperature of the part is 1150 ° C,

c) the temperature of the heating tool - 300 ° C,

d) grease - graphite + water.

4. Modeling was carried out using a specially designed group of punches, shown in Fig.7.

5. The simulation results are presented in the table.

The data given in the table express relative form change and have the principle of additivity. The relative shape change of the part does not depend on the shape of the surface being restored (cylinder, convex surface and concave surface). Figure 2 'shows the graphs of the formation of parts having the shape of the side surface of the barrel-shaped, cylindrical and saddle-shaped, respectively. The unit of measurement is a value equal to the measured size of the sample before implementation. T.O. the measured value characterizes the relative shape change of the sample, which does not depend on its initial shape.

Claims (2)

1. Device for restoring the outer surface of the head of the expanding fist by plastic deformation, characterized in that it contains a frame on which detachable sections of the matrix are installed with the possibility of forming between them in the assembled state of the cavity corresponding to the geometric dimensions of the head of the expanding fist, the upper plate with a punch holder fixed in it, in which two punches are installed, the shape of the front surface of which is turned towards the restored surface ited parts formed equidistant restored surface, and the shape of its rear surface side surface of the part needs no deformation, is flat. 2. The method of restoring the outer surface of the head of the expanding fist by the method of plastic deformation, characterized in that they pre-heat the part to the hot deformation temperature and restore it in the device according to claim 1.

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