Method of rotary forming

FIELD: process engineering.

SUBSTANCE: invention relates blanking, particularly, to cold forming, namely to rotary forming. Before rotary forming, billet central zone is subjected to local hardening. For this, free running rollers are used to form recesses, their shape and size being defined proceeding from required degree of hardening and billet material properties. Then, said recess are rolled out.

EFFECT: improved mechanical properties.

2 cl, 2 ex, 4 dwg

 

The invention relates to blanking and stamping production, and in particular to methods of cold working pressure, in particular, to rotary processing. It can be used, for example, in the manufacture of blanks for thin-walled metal bottoms.

From technical literature known method of increasing the strength characteristics of the sheet, by plastic deformation at 20...40%. Thus obtained sheets nagartovannyh rolling. At the same time, tensile strength and yield strength of the material of the sheet is increased, but decreased elongation up to 6...9%. (Archakov, Z.N. and others "Structure and properties of semi-finished products from aluminum alloys., M.: metallurgy, 1984, P.86...87)

It can be noted the following disadvantages of this method. Small value relative elongation complicates the execution of subsequent forming of sheet metal forming operations, as is the destruction of the workpiece in the process of plastic deformation. Intermediate heat treatment, in particular the annealing of the workpiece increases plastic properties, but at the same time reduces the strength properties of the workpiece material and reduces the operating characteristics of the items, as it requires increasing the thickness, and hence the mass of the product.

From technical literature is also known a method of rotating the hood, for example, the conical parts, where the first operation flat round billet clamp is fixed in the center to the base surface of the mandrel. By moving the pressing roller installed at a 90° angle to the generatrix of the mandrel is conical hood shell with a fixed angle of inclination of the generatrix (Burial NI "Rotary extractor shell parts on the machines, Meters: machinery, 1983, p.65,66, ri,a).

Study of the effect of rotation of the extrusion on the mechanical properties of metals and alloys has shown that it is similar to cold rolling. The microstructure can be seen grinding and pulling the grains in the direction of metal flow. Because of this, increase the tensile strength and the yield strength and the fatigue limit and the hardness of the material. Thus, the greater the degree of thinning, the higher limit of the tensile strength, hardness and resistance to shear and the lower the ductility. ((Burial NI "Rotary extractor shell parts on the machines, Meters: machinery, 1983 s, 109)

The disadvantage of this method is that during the rotation of the extrusion is not sufficient plastic deformation in the Central area of the blank between the mandrel and the clamp, so in this area the strength characteristics of the parts is much less than in the peripheral zone of plastice is anyone deformation. This leads to the necessity of increasing the thickness in the Central part of the membrane and to increase the mass of the product.

The technical nature of the closest analogue of the present invention can be considered as the rotational extrusion of the bottoms of the circular sheet blanks, comprising a workpiece plate along the perimeter of the ring on the mandrel, the message she rotational motion and forming a moving pressure roller (patent RF №2201831, B21D 18/00).

The above method relates to forming processing rollers without deliberate thinning of the wall of the workpiece, in this regard, during rotation of the extrusion heads is not happening hardening of the material at the expense of hard-working, characteristic of the rotary hood with deliberate thinning of the wall details.

The technical problem solved by the invention is a receiving sheet blanks reinforced plastic deformation zones.

The problem is solved in that the rotational hoods, including the workpiece plate on the mandrel, the message she rotational motion and forming a freely rotating rollers, previously in the Central zone of the workpiece conduct local hardening, for which a freely rotating rollers mold cavities, the number, shape and size determine Aut based on the desired degree of hardening, process parameters and mechanical properties of the workpiece material, and then the deepening roll.

In addition, to achieve the task, after the formation and flattening the first grooves on the workpiece is formed into additional deepening and roll, with peaks of more recesses have between vertices of the first.

Figure 1 shows the proposed sequence of rotational drawing, figure 2 - suggested sequence forming additional grooves, figure 3 - an example of executing intermediate pieces with molded Central recess and the groove 4 is an example of executing intermediate pieces before rotating hood spherical shell.

Position 1 - the initial round workpiece 2 workpiece after forming, in the particular case of two ring 3 and 4 grooves, 5 - strengthened in the Central part of the billet, after rolling it grooves, 6 - additional recess in the workpiece 7, 8 - hardened in the Central part of the billet, after rolling out of the grooves 9 of the Central recess on the intermediate blank 10, 11 - pin, 12 - clamp.

Examples of the proposed method.

- From a sheet of aluminum alloy cut, for example, a round billet 1 and still put it on the perimeter of the mandrel, had the soup of the ring groove and mounted on the faceplate of the machine. During the rotation of the platters on the blank mold cavities, for example, annular grooves 3 and 4, a freely rotating rollers. Grooves formed by stretching the metal and thinning of the workpiece in the area of the grooves. The shape and dimensions of the grooves are determined by the desired degree of hardening and are determined experimentally.

According to the results of strength tests of specimens cut from sheet stock, determine the dependence of the hardening of the workpiece material on the degree of deformation in the form:

σε=σ0+aεb,(1)

where σε- tensile strength after plastic deformation;

σ0- tensile strength to plastic deformation;

ε - deformation;

a and b are experimental coefficients.

Setting the desired value of the tensile strength after plastic deformation σεand solving equation (1), determine the necessary degree of deformation ε. Asking, for example, a curved shape forming recesses and protrusions of the value of R, and knowing the degree of deformation ε by solving the equation:

c/sinc=1+ε, (2)

where is the angle between the axis of the grooves and the straight line connecting the centers of the radii of the recesses and protrusions, determine the value of C.

The magnitude of the deepening of the grooves is determined by the formula:

H=2R(1-cosc),(3)

For example, for a sheet of aluminum alloy with a thickness of 1.0 mm requires σε=320 MPa. Knowing the values of σ0=280 MPa, a=183, b=0,64, according to the formula (1) determine the required value of ε=9.3 per cent. By the formula (2) determine the value of C=42°. By the formula (3), by setting R=5 mm, determine the amount of H=2,6 mm

As a result, in the area of the annular grooves by creating the first plastic tensile stresses, and then the plastic compression stress, is the desired hardening of the workpiece.

To obtain a more uniform hardening of the workpiece in the zone of plastic deformation on the workpiece may be formed by an additional groove 6, while the top features between the tops of the grooves 3 and 4. Received additional groove 6 is also unrolled.

- Leaf round merchantable is 1 still fixed on the perimeter of the mandrel, having an annular groove and a Central hole. The mandrel is mounted on the faceplate of the machine. During the rotation of the faceplate on the workpiece 1 is formed into a rotating rollers deepening, for example, an annular groove 3 and the Central recess 9, and receive the intermediate blank 10. The radius of curvature of the workpiece 10 in the area of the Central recess 9 is equal to the radius of curvature of the mandrel 11, which will be rotating hood on subsequent operations. The recess is formed by stretching the metal and thinning of the workpiece in the zone of deformation, ensuring the enhancement of the mechanical properties of the deformed zone. The workpiece 10 is stationary fixed to the mandrel 11 by the clamp 12 and carry out rotary hood with deliberate thinning of the wall. When rolling grooves of the mechanical characteristics of the workpiece material is increased due to the additional hard-working.

Thus, the described set of operations, you can make the workpiece with reinforced Central area.

1. The rotational hoods, including the workpiece plate on the mandrel, the message she rotational motion and forming a freely rotating rollers, wherein the pre in the Central zone of the workpiece conduct local hardening by forming a freely rotating rollers deepened the th, the number, shape and size of which is determined by the desired degree of hardening, and then the deepening roll.

2. The method according to claim 1, characterized in that after the formation and flattening the first grooves on the workpiece is formed into additional deepening and roll, with peaks of more recesses have between vertices first.



 

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EFFECT: improved mechanical properties.

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