RU2454288C2 - Method of producing parts from lot of billets from aluminium alloys or stainless steels by rotary extrusion in one or several-pass machining of sheet workpiece - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming. Sheet workpiece is arranged on rotary mandrel with lengthwise feed of spinning tool made up of forming roller. Said roller is arranged with clearance relative to mandrel. Part metal mechanical properties are adjusted in rotary extrusion with due allowance for thinning for every next part at i^th point. Then actual thickness of every next part at i^th point is defined to correct clearance between roller and mandrel at point (i+1) of the part.

EFFECT: active adjustment of mechanical properties.

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Description

The invention relates to the processing of metals by pressure, and in particular to a method for implementing the rotational extrusion process in the manufacture of parts, including shells of a liquid propellant rocket engine.

A known method of manufacturing parts of a conical or animated shape by rotational extrusion, including the deformation of the rotating workpiece by the rolling rollers, which communicate the movement in compliance with the necessary regulation by the degree of thinning in accordance with the existing graphic dependencies, changing the gap between the surface of the mandrel and the rollers. The higher the degree of thinning during rotational extrusion, the higher the mechanical properties of the treated metal (M. A. Gredor “Pressing and rotational extrusion”. - M .: Mechanical Engineering, 1971, p.67).

The disadvantage of this method is the lack of the ability to produce parts with specific mechanical properties without creating laborious graphic dependencies based on experimental data. The method of successive attempts, used in the construction of graphs, allows only approximate conclusions to be drawn.

The closest analogue of the present invention is a method for manufacturing parts with enhanced mechanical properties by rotational extrusion by one or more transitional processing of a sheet blank, including its installation on a rotating mandrel during longitudinal movement of the pressing tool installed with a gap between the mandrel and the roller. To obtain the desired increased mechanical properties of the metal in the part, before the rotational extrusion, the degree of thinning is calculated for each subsequent part with the adjustment by a coefficient determined empirically and depending on the process conditions according to the dependence proposed in the patent (patent No. 2380184, IPC B21D 22/16, 27.01. 2010).

The disadvantage of this method is the lack of the ability to produce parts with specific mechanical properties in the profile belts.

The technical task of the proposed method is to provide the possibility of manufacturing parts of a conical or animated shape, including the shells of the rocket engine, with the active regulation of the mechanical properties of the metal at the i-th point of the profile of the part with a minimum weight of the parts and an increase in their strength.

This problem is solved by a method of manufacturing parts from a batch of workpieces made of aluminum alloys and stainless steels by rotational extrusion of one or more transitional processing of a sheet workpiece mounted on a rotating mandrel, while longitudinally moving the pressing tool installed with gaps between the mandrel and the roller, providing the estimated degree of thinning for each subsequent part at the i-th point of the part profile. The calculation of the degree of thinning is performed according to the proposed dependence:

ε _{in details} = ε ₁ × K _n × Δσ _{in details} / Δσ ₁ , where

ε _{in details} - the degree of thinning at the i-th point of the profile for the n-th part;

ε ₁ - the degree of thinning during rotational extrusion of the l-th part;

K _n - coefficient taking into account the change in the conditions of rotational extrusion on each subsequent part, in contrast to the l-th part from the party, K _n = 1 - with constant process conditions;

Δσ _{in details} - the required increase in mechanical properties by tensile strength at the i-th point of the profile of the n-th part, equal to

Δσ _{in details} = Δσ _{in details} -σ _{n blanks} , where σ _{in details} and σ _{n blanks} are tensile strengths at the i-th profile point of the nth part and the n-th blank;

Δσ ₁ - the actual increase in mechanical properties during rotational extrusion of the l-th part, equal to Δσ ₁ = σ _{1 part} -σ _{1 of the workpiece} .

This manufacturing method takes into account the requirements for regulating the mechanical properties of metal parts.

The method is as follows.

The first workpiece 1 from the batch is installed on the mandrel 2, the pressing tool 3 is installed with a certain clearance from the side of the smaller diameter of the workpiece, it includes rotation of the part and movement along the generatrix, the part is made with an allowance L along the length.

On the start-up part L, the actual values of the mechanical properties σ _{1 of the part are} determined, knowing σ _{1 of the workpiece} and the actual degree of thinning is determined.

Then, for each subsequent part, the necessary degree of thinning at the i-th point of the part profile is calculated to obtain the necessary mechanical properties of the metal using the above dependence.

The calculated degree of thinning for each point of the rotary extrusion part is corrected by a coefficient K _n determined empirically, depending on the conditions of the process and heating of the part during manufacture.

The profile of the part and, accordingly, the semi-finished product is divided into the number of parts, the higher the required accuracy of obtaining the results of rotational extrusion, the greater the number of parts.

The manufacturing process is carried out in the following order.

The operation of controlling the wall thickness of the i-th profile point (pos. 4) emerging from under the pressing tool is introduced into the process of rotational drawing.

In the process of rotary drawing, the operation of recalculating the gap between the pressing tool and the mandrel at the (i + 1) point of the profile (pos. 5) is introduced with the determination of the adjustment of the existing gap based on the data of thickness measurement at the i-th point of the profile, based on the actual thickness of the semi-finished product in i -th and (i + 1) points of the profile and based on the required values of mechanical properties (σ _{B (i + 1) n parts} ) in this part of the shell according to the following relationship:

ε _n = ε ₁ × K _n × Δσ _n / Δσ ₁ with the definition of the gap adjustment value according to the dependence: Δδ _{(i + 1) n details} = δ _{in details} × ((S _{(i + 1) n details} / S _{i fact. n details} ) -1).

Then, the shell is rotationally drawn, and in the necessary places where the mechanical properties are required, profile points during the drawing process, the shell thickness obtained immediately after the pressing tool is measured at the ith point, based on this actual value, the degree of thinning and, accordingly, the gap are recalculated according to the above dependence for (i + 1) points in order to obtain the required mechanical properties. The coefficient K _n is determined empirically. K _n remains unchanged = 1, in the manufacture of subsequent from the first parts with constant conditions for the process. This is achieved by increasing the time interval between the manufacture of each part to cool the equipment to the original temperature.

If the process conditions change, the coefficient K _n for each following the first part of this batch is determined by analyzing the effect on the mechanical properties of heating the part during rotational extrusion by the test method of samples cut from the accessory part L of the part.

Example No. 1 of the method.

A sheet blank of aluminum alloy of the Amg6 brand in the form of a disk with a diameter of 1000 mm and a thickness of 25 mm is mounted on a mandrel. It is necessary to obtain a conical part - the shell of the rocket engine with a wall thickness of 18.0 mm with an increase in the tensile strength at the profile point (i + 1).

1. Make the first part with the following results:

The tensile strength σ _{1 of the workpiece} = 33.0 kgf / mm ² in the calculated place of the shell with the degree of deformation in this place

ε ₁ = (S ₀ -S ₁ ) / S ₀ = (24.8-17.9) / 24.8 = 0.278, where

S ₀ = 24.8 mm is the thickness of the initial billet;

S ₁ = 17.9 mm - the thickness of the 1st part;

The ultimate strength σ _{B 1 of the part} obtained in the 1st _part = 41.6 kgf / mm ² .

2. Make the second part from the workpiece with σ _{B 2 ref} = 33.4 kgf / mm ² - tensile strength in the 2nd original workpiece.

It is necessary to obtain in the part at the (i + 1) point of the profile σ _{B 2 the details} = 42.3 kgf / mm ² .

In the process of rotational extrusion of the 2nd part, the obtained actual thickness of the part is determined at the i-th point by measuring it, the size is entered into the computer and the clearance correction value is determined at the (i + 1) point

Δδ _{(i + 1)} according to:

Δδ _{(i + 1) 2 parts} = Δδ _{i 2 parts} × ((S _{(i + 1) 2 parts} / S _{i fact. 2 parts} ) -1)

the degree of thinning is determined from the above dependence

ε _{in details} = ε ₁ × K _n × Δδ _{in details} / Δδ ₁ or

ε ₂ = ε ₁ × K ₂ × (42.3-33.4) / (41.6-33) = 0.278 × K ₂ × 1.0348 = 0.288 × K ₂ ,

when K ₂ = 1, ε ₂ = 0.288 = (S _{(i + 1) workpiece} -S _{(i + 1) workpiece} / S _{(i + 1) workpiece)} ,

whence S _{(i + 1) details} = 0.712 × S _{(i + 1) blanks} = 17.66 mm and determine the value of the clearance adjustment at the (i + 1) point:

Δδ _{(i + 1) 2 parts} = δ _{i 2 parts} × (S _{(i + 1) 2 parts} / S _{i fact. 2 parts} -1) = 16.5 × (17.66 / 17.5) -1) = 0.15 mm, where

δ _{i 2 parts} = 16.5 mm — clearance at the i-th point of the 2nd part;

S _{i fact. 2 parts} = 17.5 mm - the actual thickness of the part at the i-th point of the 2nd part. If the process conditions change, the coefficient K _n for each following the first part of this batch is determined by analyzing the effect on the mechanical properties of heating the part during rotational extrusion by the test method of samples:

K _n = 1 + 0.03 (n-1), where n is the part number in the batch (for this equipment).

Example No. 2 of the implementation of the method.

A sheet preparation of steel 12X18H10T in the form of a bowl is mounted on a mandrel. Get the shell of the rocket engine with an animated profile with a wall thickness of 3.6 mm with an increase in tensile strength to 68 kgf / mm ² in the profile belt of the 5th point.

1. Make the first part with the following results:

The tensile strength σ _{1 of the workpiece} = 62.2 kgf / mm ² ,

S ₀ = 7.1 mm is the thickness of the initial billet;

S ₁ = 3.6 mm - the thickness of the 1st part;

ε ₁ = (S ₀ -S ₁ ) / S ₀ = - (7.1-3.6) / 7.1 = 0.493;

The obtained tensile strength in the 1st part σ _{in 1 part} = 65.0 kgf / mm ² .

2. Make the second part from the workpiece with σ _{in 2 ref.} = 62.8 kgf / mm ² - tensile strength of the 2nd initial billet.

It is necessary to obtain σ _{in 2 parts,} t. ₅ = 67.0 kgf / mm ² , σ _{in 2 parts,} t. ₆ = 69.0 kgf / mm ²

S _{0 t. 4} = 7.15 mm - the initial thickness of the workpiece at the 4th point of the profile;

S _{0 t.5} = 7.3 mm - the initial thickness of the workpiece at the 5th point,

the degree of thinning for rotational extrusion of the 2nd part at the 5th point is determined by the above relationship:

ε _{2 details v.5} = ε _{2 details v.4} × K ₂ × Δσ _{2 details} / Δσ ₁ or

ε _{2 parts} t. ₅ = ε _{2 details t. 4} × K ₂ × (67-62.2) / (68.0-62.8) = 0.0493 × K ₂ × 0.538 = 0.0265 × K ₂ , at K ₂ = 1 and at ε _{2 the details of t.4} = (7.15-S _{2 details of t.4} ) _/7.15 , where S _{2 of the details of t.4 is} measured during rolling and is equal to = 3.64 mm and ε _{2 details v.4} = 0.48.

If the process conditions change, the coefficient K _n for each subsequent to the first part of this batch is determined by analyzing the effect on the mechanical properties of heating the parts during rotational extrusion by the test method of samples:

K _n = 1 + 0.05 (n-1), where n is the part number in the batch (for this equipment).

Determine the thickness at the 5th point of the 2nd part from the formula for the degree of deformation:

ε _{2 parts} t.5 = 0.0265 = (S _{2 workpieces} -S _{2 parts} ) / S _{2 workpieces} = (7.3-S _{2 parts} ) / 7.3 of which S _{2 parts t.5} = 7.1 mm and according to:

Δδ _{2 details v.5} = δ _{2 details v.4} × (S _{2 details v.5} / S _{2 details fact. T.4} -1) determine the value of the clearance adjustment at the 5th point.

Thus, as a result of this method of rotational extrusion, parts are obtained, including the shells of the LRE nozzle, with the mechanical properties necessary at the ith point of the part profile. In designs of this type, there is a rational distribution of mechanical properties, which provides the estimated mechanical properties on the wall in the rocket engine shells, makes it possible to increase strength characteristics and reduce weight.

Claims (1)

A method of manufacturing parts from a batch of billets of aluminum alloys and stainless steels by rotational extrusion of one or more transitional processing of a sheet billet, including its installation on a rotating mandrel during longitudinal movement of the pressing tool in the form of a deforming roller mounted with a gap relative to the mandrel, characterized in that it is controlled mechanical properties of the metal of the part during rotational extrusion, taking into account the degree of thinning for each subsequent part in i point calculated according to
ε _{in details} = ε ₁ × K _n Δσ _{in details} / Δσ ₁
ε _{in details} - the degree of thinning for the i-th point of the profile in the n-th part;
ε ₁ - the degree of thinning during rotational extrusion of the l-th part;
K _n - coefficient taking into account changes in the conditions of rotation
extrusion on each subsequent part, in contrast to the l-th part from the party, K _n = 1;
Δσ _{in details} - the required increase in mechanical properties by tensile strength at the i-th point of the profile of the n-th part, equal to
Δσ _{in details} = σ _{in details} - σ _{n blanks} ,
where σ _{in the details} and σ _{n of the workpiece} are the tensile strengths at the i-th point of the profile of the n-th part and the n-th workpiece;
Δσ ₁ - the actual increase in mechanical properties during rotational extrusion of the l-th part, equal to Δσ ₁ = σ _{1 of the part} - σ _{1 of the workpiece} ,
in this case, the actual thickness of each subsequent part is determined at the i-th point and the gap between the roller and the mandrel is adjusted at the (i + 1) -th point of the part.