SU1590188A1 - Male die for producing hollow articles by hot strain - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular to the design of punches for hot extrusion of hollow parts. The purpose of the invention is to increase the durability of the punches. The punch for extruding articles such as deep glasses comprises a housing with an interchangeable working head attached thereto, in which an axial cavity is provided for cooling. The axial cavity is made stepped with its expansion in the zone of the interchangeable head, within which the surface of the cavity is made equidistant outer surface of the head. A relationship has been established for choosing the wall thickness in the zone of the interchangeable head S = KM (V / F) (J M / Σ B) N, where K is an empirical dimensional coefficient, s 2. ° С

M - coefficient of sensitivity of the material of the punch to temperature changes, 1 / ° C

V is the volume of the cavity of the head of the punch, m C

F - the surface area of this cavity, m 2

J M - the value of mass wear after 1000 m of the path of abrasion, kg / m 2

Σ B - ultimate strength of the material of the head of the punch, N / m 2

N is the coefficient of speed sensitivity, reflecting the nature of the change in the deformation resistance of the material of the punch head against the strain rate. The recommended ratio is to select the distance N = (0.4 ... 0.5) D from the bottom of the cavity of the head, on which the end of the coolant tube should be located, where D is the internal diameter of this working head surface. During operation, the punch is squeezed into the heated billet, deforming it according to the reverse extrusion scheme. The heating of the punch during operation is prevented by intensive cooling of the working cooling medium circulating in its cavity. 1 hp f-ly, 3 ill.

Description

The invention relates to the processing of metals by pressure and can be used for stamping the pressing of products such as deep glasses.

The object of the invention is to increase the resistance of the punch.

FIG. 1 shows a punch, a general view, cut in FIG. 2 - punch head, cut; in fig. 3 - typical forms of heads of punches, a section.

The punch for hot extrusion (Fig. 1) comprises a housing 1 with an outer threaded surface in the lower part and a screwed onto it replaceable working head 2 with a hollow cavity 3 for cooling. A cavity is made in the body

4, in which a tube 5 is placed for supplying an oh-dependent liquid, for example, industrial water, the end of which is located at a distance h (0.4-0.5) from the bottom of the head with an internal diameter of the bottom D (Fig. 1). Cavity; cooling zone, formed jointly by cavities 3 and 4, respectively, of the body and head of the punch, is made expanded in the lower part in the head area. In the head area, the cavity is designed in such a way that its contour is equidistant to the external contour of the punch head surface (Fig. 2). ) ,. and the wall thickness S is selected by the ratio

. | .. F be

where K is the empirical size of the 1Y coefficient, s. ° C; :

m is the coefficient of sensitivity of the material of the punch to temperature changes,

V - the volume of the cavity head poins

on.

m

t, m

F is the surface area of this in t

Losti, m; . the amount of mass wear after 1000 m of the abrasion path ,,

bc - ultimate strength of the material of the head of the punch,

n is the coefficient of speed sensitivity, reflecting the nature of the change in the resistance to deformation of the material of the punch head against the deformation rate.

The formula is derived from the following experimentally observed for M1x1x for; on-dimensionality At steady state; after the operation of the punch, a certain temperature is set on its working surface at a given punching rate. The higher this temperature, taking into account the coolant temperature, the more intense the softening of the surface layers of the metal of the punch head and the faster the irreversible plastic deformation will begin. Therefore, the dependence also includes the coefficient of sensitivity of the mother; a punch to temperature change, t, which is actually a factor included in the exponential: N.Kurnakov's diagonal law / u of resistance to deformation. And the higher

Q f5

jc

thirty

35

40

45

50

five

value, the greater the wall thickness S is required for reliable operation of the punch. The coefficient m is found from the dependence of the deformation resistance on temperature by forgulam.

. - (g,;

1p6, (T, -T ,,); In6j-ln6, t-t

L 1 -L

where 6.5 is 6, j is the strain resistance at temperatures T and Tj. With the convective heat exchange taking place in this case, a punch with a larger area, the surface of the cavity F gives a cooling medium more heat and cools more intensively. This increases its durability. It has been established that the choice of wall thickness S is influenced by the ratio of the volume of the cavity to the punching punch V to the surface area of this cavity F. The greater this ratio (V / F) turns out, the more intense the cooling of the punch and the greater the thickness of the wall can be assigned when designing a punch without significantly changing its durability. Punches of different materials resistance indicators are different. Punches made of materials with higher strength properties, characterized by a tensile strength of 6g, can be made with a smaller wall thickness. Therefore, in the equation for S, the tensile strength is in the denominator.

Experimental studies on installations of the type of FIBT-1 have established that with increasing wall thickness, the amount of mass wear per 1000 m path of abrasion 1 increases due to plastic pushing, which makes it necessary to add a relationship for S to mass wear in the formula formula.

The integral value of the deformation rate significantly affects the durability of the punch and the choice of its design parameters. An increase in the rate of defining the I-type V, and hence the rate of deformation (see the surface layers of the metal of the punch head) leads to an increase in wear and should be compensated for by an increase in wall thickness. Therefore, the formula introduces a coefficient of speed sensitivity n, reflecting the characteristic 5, 1

Terminating the change in resistance to deformation of the material of the punch head about the strain rate. Moreover, this coefficient practically does not depend on the temperature in the range of temperature variation characteristic of the conditions of operation of the punch. It can be considered as a coefficient reflecting the property of the speed sensitivity of the punch head ma- ria.

The coefficient p is found by the formulas

6,

i

--D 7-vr 6

-6-;

п, 1пСо

where 6.65 strain resistance at strain rates

. fio The empirical size coefficient K reflects the design purpose of the punch or, what is the same. The relative dimensions of the punch, for example, intended for in-depth flashing of similar products on hydraulic presses of the type. PAO-437

 .1 () .. 4-3 (.

The empirical dimensional coefficient K also serves to order the dimensions in the proposed relation.

For these working heads of various types, it is characteristic that after their installation on the housing 1, a step axial cavity is formed. This cavity expands in the region of the replacement head. Within the head, the surface of the cavity is made equidistant outer surface of the tool (replaceable head). Moreover, the wall thickness S dl

40

initial temperature of the surface of the punch (with special heating of the punch). 0.15 g / cm2 1.5 KG / M2.

In this case, the mass

wear acts as a characteristic

head material (4К5МФС).

The coefficients of the type for steel 4Х5МФС are found by the above formulas are found by the above formulas using experimental data obtained, for example

 K. Instr.

I- tn

each of the heads is determined by the shape of the UMM-5 testing machine equipped with a furnace. We have

mule, above.

Punch works as follows.

Pre-heated billet set in the matrix. During the working stroke of the press, the punch is lowered down and inserted into the workpiece. At the same time, the coolant supply is turned on. The head is in the most severe thermal conditions. The cooling fluid washes in the internal cavity of the head evenly. This achieves effective heat removal from the outer surface of the head, which

m

50

55

T, 500 ° C; 6, 1400 MPa; MPa;

1 2 og1ar. „. Oo44 (, /. S).

, CL coefficient n MPa; MPa; -0.5 s.

Claims (2)

1. A punch for obtaining hot deformation of hollow articles, containing a hollow body, a replaceable hollow working head associated with the body YU 15 20 five 0 0 ch -1 -1 its temperature, thereby increasing the durability of the head and the whole punch. Placing the coolant tube at a distance h (0.4-0.5) D from the bottom of the head ensures the vortex (turbulent) movement of the coolant in the cavity of the head, thereby ensuring its effective cooling. The punch has a replaceable head. When screwing a head on a rack inside it, a step cavity is formed (shown by a dotted line in FIG. 2). Punch material (including a replaceable head) is 4X5MFS steel (in the hardened state). The tensile strength of steel 4Х5МФС after quenching and tempering d. MPa. The amount of mass wear after 1000 m of the attrition path, obtained when abrading with the YliBT-l installation when rubbing hardened specimens from 4H5MFS steel, is (at the thermal contact temperature): t TE "S. ± T.INSTR 1100 + 200 ,,, about 27 where T, is the heating temperature of the preform before hot stamping; initial temperature of the punch surface (with special heating of the punch). 0.15 g / cm2 1.5 KG / M2. In this case, the mass wear acts as a characteristic head material (4К5МФС). The coefficients of the type for steel 4X5MPA are found by the above formulas are found by the above formulas using experimental data obtained, for example. Per g  K. Instr. I- tn  on the testing machine UMM-5, equipped with a furnace. We have m T, 500 ° C; 6, 1400 MPa; MPa; 1 2 og1ar. „. Oo44 (, /. S). , CL coefficient n MPa; MPa; -0.5 s. Invention Formula 1. A punch for obtaining hot deformation of hollow articles, containing a hollow body, a replaceable hollow working head associated with the body threaded connection and placed in the housing tube for the supply of a cooling medium, the end of which is located with a gap relative to the bottom surface of the working head, about the same, with the aim of: Increasing durability, the working head made with a cavity that exceeds the | transverse dimensions of the body cavity, | the inner surface of the working head is made of an equidistant outer surface of it, and the thickness S of the wall of the working head is determined by the ratio : .m, i / n.n F (g : where K is the empirical dimensional coefficient: c, c. WITH; ; m is the coefficient of sensitivity of the punch material I to change the temperature of the wind. ln "Ip-r-ln jp, go ----, 0 0 five five where 6 ,, 6 is the resistance to deformation at temperatures T. mT,} the volume of the cavity of the head of the punch, m; surface area of this cavity, m; the amount of mass wear after 1000 m of abrasion, the strength of the material of the head of the punch, the coefficient of speed sensitivity, reflecting the nature of the change in resistance to deformation of the material of the head of the punch from the speed of deformation. , 2. A punch according to claim 1, characterized in that the gap between the end of the tube and the bottom surface of the working head is 4-0.5) D5 g De B is the internal diameter of the bottom surface of the working head. V F Phi9 .d