RU2393937C1 - Method of producing semi-hollow rod-like stepped parts - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and can be used in producing semi-hollow rod-like stepped parts, e.g. rivets, axles and pins, at cold heading automatic machines. Method comprises cutting pre-cut length billet. Direct extrusion of billet is performed to produced blunt cavity at rod one end. Stepped semi-finished product is produced by reducing the billet in mould, clamping blunt cavity wall and sizing blunt wall at sizing gage. The latter is arranged floating in reduction strain center and providing for creating friction forces between sizing gage and blunt cavity wall in subsequent sizing. Heading is effected inside mold closed cavity with the help of rod-type punch. Then chamfers are made simultaneously on parts faces and final profile is shaped. Final head forming is performed on rod opposite end.

EFFECT: higher quality of finished products.

1 dwg

Description

The invention relates to the processing of metals by pressure and can be used in the manufacture of semi-hollow rod parts of a stepped shape such as rivets, tenon housings, shafts, axles and fingers on cold heading machines.

A known method of manufacturing semi-hollow rivets in which they cut the core workpiece of measured length and perform its deformation in several transitions with the formation of the head at one end of the rod and a blind axial cavity at the other, while in the process of deforming the workpiece, it is calibrated with bushing extrusion, direct extrusion with obtaining a deaf cavity at one end of the workpiece rod, reduction in a matrix with a conical deforming part to obtain a stepped semi-finished product with a conical transitional surface between the steps and a blind cavity located on the end of the smaller step, the diameter, depth and wall thickness of which are equal to the corresponding parameters of the finished part, and the final design of the rivet head (see RF patent No. 2107574, CL BK 1/60, bull. No. 9, 1998).

The disadvantage of this method is the low tool life on the operations of direct extrusion of the deaf cavity, reduction in the matrix and on the operation of the final formation of the head, due to non-optimal true deformations during direct extrusion of the deaf cavity. This method also does not provide the formation of a blind cavity with stable geometric parameters during the reduction operation due to free crimping of the cavity wall in the conical deforming part of the matrix. In addition, production tests showed that during the final design of the head of the part, there is a non-filling of the angle of the head from the side of the lower stage due to the high conical part of the workpiece formed when it is reduced at the previous transition. Reducing the height of the conical part of the workpiece by increasing the angle of reduction and crimping to improve the filling quality of the head during its upsetting increases the unevenness in the wall thickness and the formation of wrinkles due to compressive meridian and tangential stresses and bending when leaving the conical deforming part into a cylindrical gauge.

There is a known method of manufacturing semi-hollow rivets in which they cut a workpiece of measured length and calibrate it successively with extruding the basting, direct extrusion to obtain a blind cavity at one end of its rod, reduction in a matrix with a conical deforming and output calibrating parts to obtain a stepped semi-finished product located on the end of the smaller stage with a blind cavity and the final design of the head on the other end. The reduction in the matrix is combined with the crimping of the wall of the blind cavity and is performed on a calibrating mandrel located on the side of the end of the smaller stage outside the conical deforming part of the matrix. The axial flow of the metal of the wall of the deaf cavity and its shape are set by changing the contact friction or the configuration of the output part of the matrix with the following ratio of the dimensions of the deaf cavity: S / D _det > 0.2, where S is the wall thickness of the deaf cavity of the part; D _det - the outer diameter of the wall of the deaf cavity of the part (see RF patent No. 2175277, class B21K 1/60, B21J 5/06, bull. No. 30, 2001).

The disadvantage of this method is the low resistance of the calibrating mandrel located outside the conical deforming part of the matrix, due to the load acting on its end from the present wall thickness, which occurs when crimping the semi-finished product. Since the calibrating mandrel is located outside the conical deforming part of the matrix, it does not participate in the process of crimping the workpiece and when calibrating the workpiece in this way, shear deformations arise in the axial and radial directions. The load acting on the end face of the mandrel from the side of the deformable semi-finished product having a wall thickness difference leads to bending moments on the mandrel, which reduces its resistance. In addition, the method does not solve the problem of filling the head in the outer corner from the side of the end of the smaller step at the final transition of its formation, since an increase in the angle of reduction at the previous position leads to a sharp decrease in the resistance of the calibrating mandrel and to a deterioration in the quality of the part due to the presence and amplification of shear deformations.

Closest to the proposed one is a method of manufacturing semi-hollow rivets, which includes measuring a workpiece of measured length and calibrating it successively with extruding the basting, direct extrusion to obtain a blind cavity at one end of the workpiece rod, obtaining a stepped semi-finished product by reducing the workpiece in a die with a compression of the blind cavity wall and calibration of a blind cavity on a calibrating mandrel located floating in the focus of deformation of the crimp from the condition of ensuring the subsequent calibration of the friction forces between the mandrel and the wall of the blind cavity, as well as the final formation of the head on the other end of the semi-finished product (see RF patent No. 2220808, CL BK 1/60, B21J 5/06, Bull. No. 1, 2004).

In solving the problem of improving the durability of the mandrel and the quality of the calibrated blind cavity, the invention, although it achieves some improvement in filling the head of the finished part by reducing the height of the conical part of the workpiece at the previous transition, does not completely solve this problem - the quality of filling the head from the side of the end of the lower stage by final transfer of landing, as due to the need for a chamfer at the ends of the product at the final transition of the heading, simultaneously with head heading, it is impossible to realize the head stamping closed in the cavity of the matrix.

The objective of the invention is to improve the manufacturing quality of semi-hollow rod stepped parts due to better filling of their heads.

The problem is achieved in that in the proposed method for the manufacture of semi-hollow bar stepped parts, including cutting a workpiece of measured length, direct extrusion of the workpiece to obtain a deaf cavity at one end of its rod, obtaining a stepped semi-finished product by reducing the workpiece in a matrix with crimping the wall of the deaf cavity and calibrating the deaf cavities on a calibrating mandrel located floating in the area of crimp deformation of the crimp from the condition of ensuring the subsequent calibration of the friction forces between with the wall and the wall of the deaf cavity, as well as the final formation of the head at the other end of the rod, according to the invention, after reduction in the matrix with crimping the walls of the deaf cavity and simultaneously calibrating the cavity itself on the mandrel, they land in a closed cavity of the matrix, using a rod punch a step blank is formed, and then simultaneously form the chamfers at the ends, the full profile of the part and finally form the head.

The invention is illustrated in the drawing, which shows the technological scheme of the landing process. According to the scheme, the workpiece of measured length is cut off, then at the first landing step, the workpiece is directly extruded to obtain a blind cavity at one end of its shaft with a hole diameter dzag. At the second transition, the upsets are reduced in a matrix with crimping the walls of the blind cavity and calibrating the cavity itself on the mandrel, which is floating in the center of deformation of the crimp from the condition of providing the subsequent calibration of the friction forces between the mandrel and the wall of the blind cavity. At the third landing step in the closed cavity of the matrix, a step blank is formed using a rod punch. At the fourth transition, bevels are formed at the ends, a complete profile of the part, and finally form the head.

Landing polupustotelyh rod parts form a step, in which the relative wall thickness hollow cavity S / D _{kids '>} 0.2, and the relative depth of the cavity h _children / d _kids'> 2.5, where S - the wall thickness of the hollow cavity part, and - D _children outer the wall diameter of the blank cavity of the part, according to the proposed method, can improve the quality of the formation of the head of the product due to the formation of a stepped workpiece in a closed cavity of the matrix.

The method is proposed for implementation in the manufacture of products by cold forging on cold heading machines at the enterprise JSC "Belebeevsky plant" Autonormal "

So, the claimed invention improves the quality of semi-hollow rod stepped parts due to better filling of their heads.

Claims (1)

A method of manufacturing a semi-hollow rod-shaped step parts, including measuring a length of a workpiece of length, direct extrusion of a workpiece to obtain a deaf cavity at one end of its rod, obtaining a stepped semi-finished product by reducing the workpiece in a die with a crimped wall of a deaf cavity and calibrating a deaf cavity on a calibrating mandrel located floating in crimp deformation zone from the condition of ensuring the subsequent calibration of the friction forces between the mandrel and the wall of the blind cavity, as well as the final form head at the other end of the rod, characterized in that after reduction in the matrix with crimping the walls of the deaf cavity and simultaneously calibrating the deaf cavity on the calibrating mandrel, they land in the closed cavity of the matrix with the help of a rod punch and form a stepped workpiece, and then facets are formed at the ends , the full profile of the manufactured part and carry out the final formation of the head.

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