EP2540409A1

EP2540409A1 - Method for transverse rolling of ball products, in particular out of scrap railway rail heads, using flat tools

Info

Publication number: EP2540409A1
Application number: EP12461524A
Authority: EP
Inventors: Zbigniew Pater
Original assignee: Politechnika Lubelska
Current assignee: Politechnika Lubelska
Priority date: 2011-06-20
Filing date: 2012-06-19
Publication date: 2013-01-02
Anticipated expiration: 2032-06-19
Also published as: EP2540409B1; PL215444B1; PL395350A1

Abstract

A method for cross rolling with flat tools of products such as balls, in particular the ones obtained from heads of scrap railway rails, consists in that billet (1) in the form of a head cut off a scrap railway rail is placed between initial wedges (4 and 5) located on one side of flat tools (2 and 3), which then begin to move in the opposite directions with the same velocity (V), and the moving initial wedges (4 and 5) cut into the billet 1 and make it rotate, thereby forming a semi-finished product (6) in the form of a rod whose diameter (D1) is bigger than or equal to the diameter (D) of a ball (7), next the flat tools (2 and 3) are stopped and the semi-finished product (6) is moved to the other side of the flat tools and placed between two wedges (8 and 9) which have longitudinal grooves (10 and 11) of a semi-circular profile, then the flat tools (2 and 3) make a return motion with the same velocity (V), and during this time the wedges (8 and 9), which move in the opposite directions, form the balls (7) which are separated from one another by cutters (12 and 13) in the final stage of the rolling process. The process is done in a configuration wherein only one of the flat tools (2 or 3) moves in a sliding motion with the velocity (V), while the other tool (2 or 3) does not move.

Description

The present invention relates to a method for cross rolling with flat tools of products such as balls, in particular the ones obtained from heads of scrap railway rails.
There are numerous methods for producing balls which are then used in ball mills or rolling bearings. The most commonly employed methods include casting, die forging, and rolling. In casting, balls are cast from cast steel into permanent moulds made of metal, or so-called metal moulds. Die forging of balls is usually performed using friction presses with billets in the form of rods made from steel which contains increased amounts of carbon and manganese. Immediately after the process of die forging using eccentric presses, flash trimming is performed. The process of producing balls is most efficient if cross rolling is employed. During one roll turn, one ball is produced. Within one minute it is possible to produce even up to 160 balls of approximately 30 mm in diameter or 40 balls of approximately 120 mm in diameter. Balls are rolled in helical rolling mills equipped with two rolls, each roll having single grooves cut over the screw line, their length being generally equal to 3.5 of the coil. The axes of the rolls are inclined relative to the axis of the billet (rod), usually at the angle ranging from 3° to 7°. In the course of rolling, the rolls turn in the same direction, while the billet turns in the opposite direction. In order to obtain good rolling results, the billet diameter should approximately equal 0.97 of the diameter of finished balls. The diameter of the rolls is from 5 to 6 times bigger than the diameter of balls. Information on helical rolling of balls is presented in the following book: W. Dobrucki, Zarys obróbki plastycznej metali, Wydawnictwo "Śl
sk," Katowice 1975.
There is another method for cross-wedge rolling of four balls, described in: Z. Pater, Walcowanie poprzeczno-klinowe, Wydawnictwo Politechniki Lubelskiej, Lublin 2009. This method consists in using two flat tools which move in the opposite directions, thereby forming balls from the billet in the form of a rod whose diameter is equal to the ball diameter. The tools used in rolling consist of two parts: a forming wedge and a cutting pad. The forming wedge, which is of a typical shape, has longitudinal wedge grooves of a transverse circular profile, and the distance between the grooves is smaller than the diameter of the ball being formed. The effect of the forming wedge is that balls connected by cylindrical connectors, whose diameter is approximately half of the ball diameter, are produced. To separate the formed balls a cutting pad needs to be used, the effect of which is that the connectors are transformed into the missing parts of the balls. A characteristic of this is that during the cutting process, the balls are drawn aside by the grooves, which are located in this part of the tool at the angle towards the rolling direction, or the direction in which the wedge tool moves.
The essence of the method for cross rolling with flat tools of products such as balls, in particular the ones obtained from heads of scrap railway rails, is that a billet in the form of a head cut off a scrap railway rail is placed between two initial wedges located on one side of the flat tools which then begin to move in the opposite directions with the same velocity, and the moving initial wedges cut into the billet and make it rotate, thereby forming a semi-finished product in the form of a rod whose diameter is bigger than or equal to ball diameter. Next the flat tools are stopped and the semi-finished product is moved to the other side of the tools and placed between two wedges which have longitudinal grooves of a semi-circular profile, then the flat tools make a return motion with the same velocity, and during this time the wedges, which move in the opposite directions, form balls which are separated from one another by cutters in the final stage of the rolling process. The process is done in a configuration wherein only one of the flat tools moves in a sliding motion, while the other does not move.
One advantage of the invention is that it makes possible to simultaneously form many balls, the quantity of which depends on the tool width. Thanks to the application of this invention, it is possible to form balls using cheap material obtained from scrap railway rails. The invention is environment-friendly as its application will decrease the amount of scrap for metallurgical processing that reaches steel mills. Another advantage of the invention is that it allows for eliminating idle running from the rolling process when the tools move back to their starting position.
An exemplary embodiment of this invention is shown in the attached drawings, wherein Fig. 1. shows the beginning of the cross rolling process as well as the type of the billet used, Fig. 2 illustrates the moment of the rolling process when the semi-finished product in the form of a rod is produced by the initial wedges, and Fig. 3 shows the end of the rolling process and the produced balls.
The method for cross rolling with flat tools of products such as balls, in particular the ones obtained from heads of scrap railway rails, consists in that the billet 1 in the form of a head cut off a scrap railway rail is placed between the initial wedges 4 and 5 located on one side of the flat tools 2 and 3, which then begin to move in the opposite directions with the same velocity V, and the moving initial wedges 4 and 5 cut into the billet 1 and make it rotate, thereby forming the semi-finished product 6 in the form of a rod whose diameter D1 is bigger than or equal to the diameter D of the ball 7, next the flat tools 2 and 3 are stopped and the semi-finished product 6 is moved to their other side and placed between two wedges 8 and 9 which have longitudinal grooves 10 and 11 of a semi-circular profile, then the flat tools 2 and 3 make a return motion with the same velocity V, and during this time the wedges 8 and 9, which move in the opposite directions, form the balls 7 which are separated from one another by the cutters 12 and 13 in the final stage of the rolling process. The process is done in a configuration wherein only one of the flat tools 2 or 3 moves in a sliding motion with the velocity V, while the other tool 2 or 3 does not move.

Claims

A method for cross rolling with flat tools of products such as balls, in particular the ones obtained from heads of scrap railway rails, consists in that a billet (1) in the form of a head cut off a scrap railway rail is placed between initial wedges (4) and (5) located on one side of flat tools (2) and (3), which then begin to move in the opposite directions with the same velocity (V), and the moving initial wedges (4) and (5) cut into the billet (1) and make it rotate, thereby forming a semi-finished product (Q) in the form of a rod whose diameter (D1) is bigger than or equal to the diameter (D) of a ball (7), next the flat tools (2) and (3) are stopped and the semi-finished product (6) is moved to their other side and placed between two wedges (8) and (9) which have longitudinal grooves (10) and (11) of a semi-circular profile, then the flat tools (2) and (3) make a return motion with the same velocity (V), and during this time the wedges (8) and (9), which move in the opposite directions, form balls (7) which are separated from one another by cutters (12) and (13) in the final stage of the rolling process.
A method according to claim 1, whereby the process is done in a configuration wherein only one of the flat tools (2) or (3) moves in a sliding motion with the velocity (V), while the other tool (2) or (3) does not move.