[0001] The subject of the invention is a method of rolling extrusion with regulated axis
spacing of axi-symmetrical stepped parts.
[0002] Until now, there exist and are applied numerous methods of axi-symmetrical stepped
forgings manufacturing, full and hollowed, which are used as semi-finished products
of stepped shafts, sleeves and others. The most widely applied methods include: die
forging on presses and hammers, drawing, forging and piercing, rotary swaging, rotary
forging, internal high pressure forming, rolling extrusion in cold, rolling extrusion
in cold with deep drilling and cross-wedge rolling. These processes are described
in details in the literature by Bartnicki. J, Pater Z. "Cross-wedge processes of hollowed
products", ed. Lublin University of Technology, Lublin 2005. As it is given by the
authors, the largest products precision is obtained in the drawing processes, however,
limits connected with this technology application for manufacturing of hollowed parts
are small possibilities within the scope of the obtained elements shapes. The forging
technology finds application only in the case of forming of shafts with large dimensions
and weight. Yet, piercing is used for thick-walled and short sleeve production. Swaging
processes allow for reduction of bars and tubes diameters. Parts formed by means of
that method are characterized by large precision, and, at forging on a mandrel, they
can possess very accurate cylindrical and conical holes. Another method of hollowed
parts manufacturing is hydrostatic extrusion, which allows for forming of products
of assumed geometry. In this method, a product is formed under high pressure caused
in the element inside. Cold extrusion processes are widely applied in industry for
manufacturing of hollowed parts, they form due to extruding by the die hole on mandrel.
Recently, numerous ways of forming of hollowed parts basing on cross-wedge rolling
and wedge-rolls rolling methods have been worked out. In the cross-wedge rolling and
wedge-rolls rolling methods at least one of the forming tools constitutes a flat wedge
rolled on a roll, which reduces billet diameter by driving into it, displacing certain
metal volume at sides. In the result the product undergoes elongation during forming
and the wall thickness in the area of the formed necking lowers. This leads to the
product weakening in the area of the rolled step and imposes application of thick-walled
billets, which can be formed only in hot conditions Additionally, this method requires
usage of complex wedge tools of large dimensions, which results in large implementation
costs of the cross-wedge rolling technology.
[0003] From Polish patent claim number
P.392275 is well known a way of rolling extrusion of hollowed parts, which is based on forming
of a semi-finished part in the form of a sleeve or a tube part between three rotating
tools. Yet, one of the tools or all tools move additionally in the direction of the
semi-finished part axis, putting it into rotation and reducing particular steps of
formed multi-stepped shaft. A characteristic feature of this process is tools outline
representation on the part external surface, in the result of which section reduction
and increase of the product wall thickness take place.
[0004] From Polish patent claim number
P.393242 is known a way of forming of hollowed products be means of rolling extrusion, which
is based on forming of axi-symmetrical hollowed parts from a semi-finished product
in the form of a tube. In the described in the claim rolling extrusion process, the
semi-finished product is placed in the rotational head, later, it is displaced into
the direction of three rotational tools, which are placed around the billet axis every
120°. In the result of tools action, the diameter of external billet pivot is reduced
and hollowed stepped part is obtained.
[0005] The issue of rolling extrusion process with regulated axis spacing , of stepped axi-symmetrical
parts, is the fact that the formed semi-finished product in the form of a bar or a
tube part is placed in the front rotational holder seat and the seat of back rotational
holder, next the front rotational holder and back rotational holder together with
semi-finished product move with a translational motion with constant velocity into
the workspace, which is made by the same three formed rolls , next the same three
formed rolls are put into rotational motion in the same direction and with the same
velocity, then revolution motion of the same three formed rolls is activated and the
same three formed rolls are brought closer to the semi-finished product, yet, rotary
movement trajectories of the same three formed rolls are of spiral shape, next the
semi-finished product is affected by the formed rolls working surfaces and the semi-finished
product is put into rotary motion with constant velocity in the direction opposite
to the direction of rotations of the same three formed rolls, and, at the same time
the semi-finished product is squeezed by working surfaces and the necking is formed
on the part circumference.
[0006] An advantage of the invention is the fact that it allows for metal forming of multi-stepped
parts of full and hollowed shafts, due to which mechanical characteristics of such
manufactured products improve. Thanks to the application of automatic change of the
axles distance during rolling extrusion process of parts the process technological
possibilities enlarge in comparison with used so far manufacturing methods. The invention
gives the opportunity of application of one set of simple rotary tools in the form
of rolls for manufacturing of various products, both full and hollowed. The invention
is universal and allows for forming of parts from all alloys destined for metal forming.
[0007] The invention is presented in the example of realization in figure, in which Fig.1
shows the beginning of the process and tools and semi-finished product placement in
the front view, Fig.2-view from the side of the process and tools at the beginning
of rolling extrusion, Fig.3-isometric view of the process, tools and semi-finished
product at the beginning of rolling extrusion, Fig.4-view from the front of the process
and tools and part placement at the end of rolling extrusion, Fig.5-view of the side
of the process and tools at the end of extrusion, yet, Fig.6-isometric view of the
process, tools and forging at the end of rolling extrusion.
[0008] The way of rolling extrusion with regulated axis spacing of axi-symmetrical stepped
parts is based on that a formed semi-finished product
3 in the form of a bar or tube part is placed in the seat of the front rotary holder
1 and in the seat of the back rotary holder
2. Next, the front rotational holder
1 and back rotational holder
2 together with semi-finished product
3 move with a translational motion with constant velocity
V into the workspace. The workspace is made by the same three
4a,
4b and
4c formed rolls. Next the same three
4a,
4b and
4c formed rolls are put into rotational motion in the same direction and with the same
velocity
n1. Then revolution motion of the same three
4a,
4b and
4c formed rolls is activated with the velocity
n2 and the same three
4a,
4b and
4c formed rolls are brought closer to the semi-finished product
3. Rotary movement trajectories
7a,
7b and
7c of the same three
4a,
4b and
4c formed rolls are of spiral shape. Next the semi-finished product
3 is affected by the
4a,
4b and
4c formed rolls working
4a1,
4a2,
4b1,
4b2,
4c1 and
4c2 surfaces and the semi-finished product
3 is put into rotary motion with constant velocity
n3 in the direction opposite to the direction of rotations of the same three
4a,
4b and
4c formed rolls. At the same time the semi-finished product
3 is squeezed by working
4a1,
4a2,
4b1,
4b2,
4c1 and
4c2 surfaces and the necking
5 is formed on the part circumference
6.
1. The way of rolling extrusion with regulated axis spacing of axi-symmetrical stepped
parts characterized in that a formed semi-finished product (3) in the form of a bar or tube part is placed in the seat of the front rotary holder
(1) and in the seat of the back rotary holder (2), next, the front rotational holder (1) and back rotational holder ( 2) together with semi-finished product (3 )move with a translational motion with constant velocity ( V ) into the workspace, which is made by the same three (4a), (4b) and (4c) formed rolls, next the same three (4a), (4b) and( 4c) formed rolls are put into rotational motion in the same direction and with the same
velocity (n1), then revolution motion of the same three (4a), (4b) and (4c) formed rolls is activated with the velocity( n2) and the same three( 4a), (4b) and (4c) formed rolls are brought closer to the semi-finished product( 3), yet rotary movement trajectories (7a), (7b) and (7c )of the same three (4a), (4b) and (4c) formed rolls are of spiral shape, next the semi-finished product (3) is affected by the (4a), (4b) and (4c) formed rolls working (4a1), (4a2), (4b1), (4b2), (4c1) and (4c2) surfaces and the semi-finished product (3) is put into rotary motion with constant velocity( n3) in the direction opposite to the direction of rotations of the same three (4a), (4b) and (4c) formed rolls and at the same time the semi-finished product (3) is squeezed by working
(4a1), (4a2), (4b1), (4b2), (4c1) and (4c2) surfaces and the necking (5) is formed on the part circumference (6).
