SU1291263A1 - Method of producing blanks for consequent extrusion in die and machining by cutting - Google Patents

Abstract

The invention relates to the field of metal forming and allows to increase the durability of the working tool during rapid compression by creating hydrodynamic conditions for contact friction by using a special blank. This preform is produced by profiling the original bar preform until a regular polygon is formed in cross section. A layer of lubricant is applied to the latter. After that, the layer is calibrated, giving it a cshshn-dry form. The use of such a preform also makes it possible to improve the accuracy of its centering in the die, for pressing. 2 hp f-ly, 14 ill. with S cl

Description

The invention relates to the processing of metals by pressure and can be used for the manufacture of blanks for extrusion of long products.

The purpose of the invention is to increase the durability of the working tool by creating hydrodynamic conditions for the contact friction during extrusion.

Fig. 1 shows a rod after drawing, a transverse polygonal section J in Fig. 2, a piece billet with a layer of technology with extrusion strokes, a cross section; 4a 4g, 3 - the same, with lubrication after calibration), Fig. 4 - the blank before extrusion, the initial position in FIG. 5 is section A-A in FIG. 4, in FIG. 6 the moment of lubricant calibration during pushing the workpiece into the cavity of the receiving part of matrix J in FIG. 7 is section B-B in FIG. .6; Fig. 8 shows the final stage of extrusion; in Fig. 9, section B-B in Fig. 8; 10 - section GG on Fig; FIG. 11 is a variant of extrusion in a matrix with an extended conical section of low taper, and FIG. 12 is a section DD in FIG. eleven; FIG. 13 is a sectional view E — E of FIG. 11 in FIG. 14 — SECTOR MF in FIG. eleven.

The method is carried out as follows.

The raw material in the form of hot-rolled rods or wire with a circular cross section is first dragged, giving it a regular polygonal cross section (Fig. 1) whose contour 1 is located within the allowance 5 for subsequent cutting, and the number of sides of the polygon is determined by

arccos

R-s r

R s

where n is the number of sides of a regular polygon (the closest larger integer) J radius of the circumscribed circle is one-sided allowance. After cutting the rods, a layer of molten technological lubricant is applied to the surface of the latter; 2, which, while frozen, takes shape repeating

0

five

five

0

five

cut surface of the workpiece. Then, the workpiece 3 is placed in the upper part of the die cavity 4 of the stamp for extrusion, made with regard to the increase in the transverse size of the workpiece due to the lubricant layer. At the initial stage of the working stroke of the punch 5, the workpiece 3 is pushed into the matrix 4, as a result of which the lubricant layer 2 is calibrated, which takes on a cylindrical shape from the outside (Figures 6 and 7). This ensures the installation of the workpiece 3 in the matrix 4 for fit, corresponding to h 6 / H7, and the appearance of some pre-pressure in the lubricant layer.

To prevent the displacement of the lubricant 2 into the gap between the die 4 and the punch 5 during the extrusion stroke, the latter is provided with a seal 6. capable of withstanding high hydrostatic pressures. The excess grease 7 is squeezed up (Figs. 6 and 8) and is removed from the die by any known method, for example, blown off or sucked.

Due to the fact that the angle between the faces of the workpiece is blunt, great efforts are required for precipitating the rebar, and as they see, the volume of the deformation zone increases, and, accordingly, the resistance to deformation also increases. This eliminates the occurrence of the ordering of the JTOB and the closure of the lubricant and inhibits the growth of the grip of the contact side surface. In the zone of entry into the working section of the matrix 4, the pressure in the lubricant quickly increases, and it flows along the surface of the moving workpiece until it reaches the code from the matrix. Due to the constant backing from the side of the punch, a stable hydrostatic layer is maintained, on which the workpiece

pops up

and the process goes

0

five

with the most favorable conditions; Viyami friction, i.e. there is no direct contact between the workpiece and the tool, and the usual friction is maintained only along the edges of the workpiece, whose surface area is minimal.

This embodiment of the method of manufacturing blanks provides a clear coaxial fixation of the blank along the edges in the cavity of the receiving part of the matrix 4 along its axis, thereby “ensuring a uniform axisymmetric distribution of the lubricant over

surface of the workpiece, which in turn guarantees the stability of the hydrodynamic process.

The favorable friction conditions that occur both in the cavity of the receiving part of the matrix 4 and in its point allow extrusion of long workpieces (L / DS 5) with sufficiently large relative reductions (not less than 60%).

In this case, due to the fact that the cut given to the workpiece by drawing is placed within the allowance for subsequent machining, it is easily removed from little or undeformed areas of the extruded part 8, for example, by grinding. In the case of a decrease in the number of faces compared to the optimal number, determined by this dependence, there is an unjustified increase in the stock. This in turn increases the consumption of metal and the complexity of the processing of stamped parts. An increase in the number of faces leads to an excessive decrease in the thickness of the lubricant layer, the disappearance of the effect of hydrodynamic friction, an increase in the magnitude of the contact friction between the workpiece and the cavity walls of the receiving part of the matrix 4 and to its increased wear. The load on the punch is also increased and its durability is reduced.

Calibration of the lubricant ensures its minimum thickness on the ribs, which corresponds to the usual extrusion conditions, which is necessary for coaxial fixation of the workpieces.

Example A billet is made to obtain the part by pressing it out of steel 45 and dimensions with a ratio of length to diameter L / D 5. The workpiece is deformed after it is made in cross section

five

1263

a cross section of a polyhedron shape with a specific force of 1600–1800 MPa. The deformation process takes place without destroying the tool due to the constant repressing of the workpiece in the die cavity, which eliminates the sharp intensity of the growth force.

Claims (3)

Invention Formula A method of making blanks for subsequent extrusion in the chip and machining, including profiling the original bar stock, dividing it into separate blanks and applying a process lubricant layer on their surface, characterized in that, in order to increase the durability of the working tool, The bar stock is given the shape of a regular polygon whose cross section is within the allowance for subsequent machining, and the number of sides gougolnika determined from the relationship thirty P arccos R-f where n is the number of sides of a regular polygon (the nearest greater integer) J R is the radius of the circumcircle, 6 is a one-sided allowance. 2. Method according to Claim 1, characterized by the fact that after applying the layer, the lubricant is calibrated, giving it a cylindrical shape. 3. A method according to claim 2, characterized in that the calibration of the lubricating layer is carried out in a die for subsequent pressing. Fl / rr 1291263 FIG. five Fig.8 rS Fig.: YY f14g.Yu step Editor I. Gorna FIG Compiled by A. Bystrov Tehred I.Popovich, Proofreader L. Pilipenko Order 77/12 Circulation 583 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, the city of Uzhg (rod, Proektna str., 4