RU2391172C1 - Method of single-pass punching of rod parts with cavity in bulge part - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: invention refers to metal pressure processing and can be applied in punching of bolts with cavity in bulge part, i.e. in bolthead. Blanc part to be deformed, of relative length within tolerance limits, is placed in the punch cavity. The blanc undergoes upsetting, broaching and shaping by simultaneous application of puncheon and broach. Counterpressure equal to the value of bulge upsetting force is applied to puncheon. Puncheon is shifted in axial direction opposite to broach movement. Shift size is equal to the depth of broached cavity in the bulge. ^ EFFECT: improved quality of rod parts with a cavity in bulge part. ^ 3 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure and can be used, for example, when stamping bolts with a cavity in the thickening, i.e. in the head.

A known method of single-pass stamping of rod parts with a cavity in the thickening, which consists in placing a deformable part of the workpiece, the relative length of which does not exceed the allowable, in the die cavity, upsetting, piercing and molding of the workpiece by means of a punch and piercing. In this method, in the process of deformation, which consists in landing, flashing and molding the workpiece, first by means of flashing, the wrought part of the workpiece is disembarked, and then flashing and punching are performed by flashing and punch (Bryukhanov A.N. Forging and die forging. / A. N. Bryukhanov. - M.: Mechanical Engineering, 1975, - p. 275, 276, fig. 249; p. 280, 281, fig. 252).

The disadvantage of this method is the low quality of parts caused by one-sided filling of the die cavity and uneven distribution of metal in the radial direction due to the inevitable displacement of the axis of the core blank relative to the piercing axis in the initial period of deformation. (Brukhanov A.N. Forging and die forging. / A.N. Bryukhanov. - M.: Mechanical Engineering, 1975, p. 281).

A known method of single-pass stamping of rod parts with a cavity in the thickening, which consists in placing a deformable part of the workpiece, the relative length of which does not exceed the allowable, in the die cavity, upsetting, piercing and molding of the workpiece by means of a punch and piercing. At the same time, in the process of deformation, which consists in upsetting, flashing and molding the workpiece, first, the deformable part of the workpiece is planted with firmware, and then with firmware and molding by the simultaneous action of the punch and firmware. Moreover, in the process of deformation, a backpressure force is applied to the firmware and the excess metal is displaced into the resulting compensation cavity, which eliminates the appearance of burrs and improves the quality of parts. This technical solution is the closest in the set of essential features and is selected as a prototype (copyright certificate SU 1063519, class B21J 5/08, B21K 1/46).

The main disadvantage of the described method of single-pass stamping of rod parts with a cavity in the thickening is the reduced quality of the parts, since during the initial deformation of the workpiece by piercing, the axis of the workpiece relative to the piercing axis is inevitable. This leads to uneven distribution of metal in the radial direction and one-sided non-filling of the stamp, which leads to reduced quality of parts (Bryukhanov A.N. Kovka and die forging. / A.N. Bryukhanov. - M.: Mechanical Engineering, 1975, - p. 281) .

The basis of the invention is the task of improving the quality of rod parts with a cavity in the thickening.

To solve the problem in a method of single-pass stamping of rod parts with a cavity in the thickening, consisting in placing a deformable part of the workpiece, the relative length of which does not exceed the allowable, in the die cavity, upsetting, piercing and molding the workpiece by means of a punch and piercing with the application of a back pressure, according to the invention disembarkation, firmware and molding are carried out by simultaneous impact on the workpiece of the punch and firmware, applying to the punch back pressure equal to Eli thickening landing, and moving it in the axial direction opposite to the movement of the piercing mandrel by an amount equal to the depth of the cavity in the thickening stitched.

In the initial period of upsetting, flashing and molding, the co-axial fixation of the preform relative to the punch and flashing is ensured by the simultaneous action of the punch and the piercing on the workpiece due to the contact frictional forces arising on the entire end surface of the workpiece, therefore, uniform distribution of metal in the radial direction and favorable filling occurs during the flashing process die cavity during molding, which ensures high quality of parts (Brukhanov A.N. Forging and die forging. / A.N. Bryukhanov. - M.: Mechanical Engineering, 197 5, - p. 281).

The proposed invention is illustrated in the drawing, where figure 1 shows the initial position of the stamp, figure 2 - the position of the stamp at the time of completion of the landing and firmware thickening; figure 3 - position of the stamp at the end of the molding.

The method of single-pass stamping of rod parts with a cavity in the thickening is implemented as follows.

The deformable part of the workpiece 1, the relative length of which does not exceed the allowable, is placed in the cavity 2 of the stamp 3 on the ejector (not shown in the drawing). Then carry out the landing, firmware, molding by simultaneously acting on the workpiece of the punch 4 and firmware 5, placing them in the holder 6. The holder 6 and firmware 5 are mounted on the top plate 7 of stamp 3 (figure 1). In the process of deformation, a counter-pressure force of the elastic element 8 is applied to the punch 4, which is equal in magnitude to the landing force of the thickening of the workpiece 1, and it is displaced in the axial direction opposite to the movement of the piercing 5 by an amount equal to the depth of the stitched cavity 9 in the thickening of the workpiece 1. By the time it is finished disembarkation and firmware, the punch 4 with its rear end surface 10 reaches the stop 11, made in the form of a cylindrical thickening on the firmware 5 (Fig.2). Then carry out the molding of the thickening 12, during which the punch 4 is moved as a unit with the piercing 5. The resulting part 13 is removed with a pusher (figure 3).

Example

A pilot batch of bolts from a core blank with a diameter of D = 12 mm and a length of 94 mm was stamped. The workpiece material is steel 40X. The diameter of the thickening (head) of the bolt is D _g = 20 mm, the cavity in the head is turnkey hexagon S = 8 mm, depth h = 8 mm. The height of the bolt head N _g = 11 mm. The length of the deformable part of the workpiece l _in = 29 mm, the relative length ψ = l _in /D=29/12=2,4,4<2.5, which satisfies the condition of free landing of the core workpiece (Bryukhanov A.N. Kovka and die forging. / A. H. Bryukhanov.- M.: Mechanical Engineering, 1975, - p. 281).

The stamping temperature is 900 ° C. The item was received in one stroke of the KA0030 model press with a force of 1MN.

The calculation of the parameters of the elastic element is carried out in the following order:

1) determine the force of the end of the landing

where k = 2.2 is a coefficient selected depending on the ratio of the size of the thickening (Brukhanov A.N. Kovka and die stamping: / A.H. Bryukhanov. - M.: Mechanical Engineering, 1975, - p. 285);

σ = 71 MPa — tensile strength of steel 40X at stamping temperature;

F _to = 314 mm ² - the area of the end surface of the workpiece at the time of completion of disembarkation;

усилие сжатия одной пружины Р_сж=610 кгс (Романовский В.П. Справочник по холодной штамповке. / В.П.Романовский. - Л.: - Машиностроение, 1979, - с.383, табл.177);2) according to the upsetting force, a set N of eight plate springs with an outer diameter of 32 mm and an opening diameter of 15 mm is selected as the elastic element. Spring thickness t = 2.9 mm; spring deflection

a spring compression force P = 610 kgf _{compression channel} (Romanovsky VP Handbook of cold forming / V.P.Romanovsky - L .: - Machinery, 1979 - s.383, tabl.177..);

3) determine the compression force of the set of springs:

which corresponds to the landing force at the time of its completion;

4) determine the height of the set of springs in the initial state:

5) determine the amount of compression of the elastic element by the time the end of the landing:

h _cr = f · N = 1.0 · 8 = 8 mm,

which is consistent with the displacement of the punch during upsetting and firmware, equal to the depth of the cavity in the thickening h = 8 mm.

The rod blank 1 with a length of 94 mm is placed in the stamp 3 on the ejector so that the length of the deformable part of the blank 1, equal to 29 mm, is located in the cavity 2 of the stamp 3. During the course of the top plate 7, the ferrule 6 and the piercing 5, mounted on the plate 7, and also the punch 4 moves down. In this case, the punch 4 is squeezed to the lowest position by the elastic element 8 until the end surfaces of the punch 4 and the firmware 5 are aligned in the same plane. In the initial period of disembarkation, firmware and molding, the workpiece 1 and the firmware 5 are coaxially fixed to the blank 1 relative to the punch 4 and piercing 5 due to contact friction forces arising on the entire end surface of the workpiece. At this point, the punch 4 enters the cavity 2 of the stamp 3 and is centered in this cavity. Further, as the upsetting force increases, the punch 4, overcoming the back pressure of the elastic element 8, is displaced in the axial direction opposite to the movement of the piercing 5 by 8 mm, equal to the depth of the pierced cavity, to the stop 11. After this, the thickening 12 is formed, the process of which the punch 4 and firmware 5 are moved as a whole, and the excess metal is forced into the core part of the part 13 as a result of the displacement of the ejector based on the elastic element (not shown in the drawing).

The main parameters of the experimental stamp and the dimensions of the stamped bolts correspond to the drawing shown in figures 1-3.

The resulting bolts had high surface quality and dimensional accuracy. There were no burrs on the surface of the parts; no weights were observed at the edge of the cavity in the bolt head.

Claims (1)

A method of single-junction stamping of rod parts with a cavity in the thickening, comprising placing a deformable part of the workpiece, the relative length of which does not exceed the allowable, in the die cavity, upsetting, flashing and molding the workpiece by means of a punch and flashing with the application of back pressure, characterized in that the upsetting, flashing and forming is carried out by simultaneous impact on the billet of the punch and piercing with the application to the punch of a counter-pressure force equal in magnitude to the landing force of the thickening, and with iem its axially opposite movement piercing mandrel by an amount equal to the depth of the cavity in the thickening stitched.

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