Forging press for hot forging of asymmetric to symmetric rail and process of forging thereof

This application is a continuation-in-part of pending International Application No. PCT/IN2021/051109 filed Nov. 27, 2021, which claims priority to Indian Patent Application No. 202031053044 filed Dec. 5, 2020 and hereby incorporates both applications by reference in their entireties.

The present invention relates to a forging machine for progressive hot end-forging of asymmetric to symmetric rail and a process of hot end-forging of asymmetric to symmetric rail.

Forging is a method of deforming steel in a heated condition to a predetermined shape using a hammering or pressing method. Hydraulic pressing systems can be categorized generally as either (a) open die or (b) close die. In open die systems, a heated metal blank is pressed between two steel plates or die. Normally, a bottom platen is fixed and the top platen is movable. Pressing is done by means of a double acting hydraulic cylinder. In closed die forging, the heated metal blank is placed in a die resembling a mold, which confines the metal work piece to the die and causes it to take on the shape of the die.

The state of the art is to heat a rail in a heater and conduct three consecutive forging operations as shown in. According to the state of the art, a forgepresses a top diesa,b, andc moving along a vertical axis only. The bottom diesa,b, andc is stationary. At present, all three forging operations are carried out on a hydraulic press fitted with a die blocka,b in which all three pairs of dies are fitted side by side and a rail is shifted and rotated as per the configuration and orientation of the dies. The shifting, rotation and positioning of the rail are carried out by manipulators. The manipulator has to be fast and accurate so that time is not wasted, which would result in cooling of the rails.

In order to make the process faster, cost effective, and to decrease rejection rate, embodiments of the present invention provide a combination of hydraulic presses and an unique press configuration for end-forging of asymmetric rail to symmetric rail, as well as a novel end-forging manufacturing process. Symmetric rail is regularly used by Railway Authorities.

The present invention provides an asymmetric to symmetric rail forging press, comprising: a roller table () having one translational axis, the roller table being adapted to receive a railroad rail () and translate a railroad rail fore and aft along the one translational axis; an induction heater () adapted to receive an end portion of a railroad rail, the induction heater being laterally movable between a working position in line with a railroad rail, and a home position not in line with the railroad rail; a first forging station in line with the roller table () and adapted to receive a railroad rail therefrom, the first forging station comprising a first pair of opposing horizontal hydraulic cylinders (a,b) having horizontal strokes and driving a first set of horizontal forging dies (), and a first top hydraulic cylinder () having a vertical stroke, the first top hydraulic cylinder being aligned to vertically impinge on the first set of horizontal forging dies during a horizontal forging operation, and the first forging station further including two clamps spaced apart along the length of a railroad rail and adapted to fix the position of a railroad rail during a forging operation; a second forging station in line with the roller table () and adapted to receive a railroad rail from the first forging station, the second forging station comprising, a second pair of opposing horizontal hydraulic cylinders (a,b) having horizontal strokes and driving a second set of horizontal forging dies (), and a second top hydraulic cylinder () having a vertical stroke and driving a top die (), and the second forging station further including a clamp adapted to receive an end of a railroad rail and fix the position of a railroad rail during a forging operation; and the top die () being linearly translatable between two working positions corresponding to a first portion (a) of the top die and a second portion (b) of the top die, wherein the first portion (a) of the top die includes a lateral step () running the length of the first portion (a), and wherein the second portion (b) of the top die is flat, omitting the lateral step ().

The invention further provides a process for asymmetric to symmetric rail forging comprising the steps of: mounting a rail to a roller table in line with a first forging station, the roller table being adapted to drive the rail along one translational axis; positioning an induction heater between the roller table and the first forging station; driving the rail into inductive communication with the induction heater; inductively heating the rail to a predetermined forging temperature; driving the rail to a first forging station; clamping the rail at ends of a working section of the rail; pressing a first set of horizontal forging dies into a head portion of the rail and into a first section of the web portion of the rail; translationally driving a set of add-on dies to a position stacked vertically on the first set of horizontal dies; pressing the first set of horizontal forging dies and the add-on dies into the head portion of the rail, the first section of the web portion of the rail, and a second section of the web portion of the rail; driving the rail to a second forging station; clamping the rail at three points including an end of the rail, a middle portion of the rail and an unworked portion of the rail; pressing a second set of horizontal forging dies into the head portion and the web portion; pressing a first portion of a top die, from a first position, into a foot of the rail; translationally driving the top die from the first position to a second position; and pressing a second portion of the top die into the foot of the rail.

Other benefits and advantages will become apparent to those skilled in the art to which it pertains upon reading and understanding of the following detailed specification.

As used herein the terms “embodiment”, “embodiments”, “some embodiments”, “other embodiments” and so on are not exclusive of one another. Except where there is an explicit statement to the contrary, all descriptions of the features and elements of the various embodiments disclosed herein may be combined in all operable combinations thereof.

Language used herein to describe process steps may include words such as “then” which suggest an order of operations; however, one skilled in the art will appreciate that the use of such terms is often a matter of convenience and does not necessarily limit the process being described to a particular order of steps.

Conjunctions and combinations of conjunctions (e.g. “and/or”) are used herein when reciting elements and characteristics of embodiments; however, unless specifically stated to the contrary or required by context, “and”, “or” and “and/or” are interchangeable and do not necessarily require every element of a list or only one element of a list to the exclusion of others.

Terms of degree, terms of approximation, and/or subjective terms may be used herein to describe certain features or elements of the invention. In each case sufficient disclosure is provided to inform the person having ordinary skill in the art in accordance with the written description requirement and the definiteness requirement of 35 U.S.C. 112.

One embodiment of the present invention is a forge configured for hot end-forging asymmetric rail to symmetric rail.

Some embodiments include a two forging positions and an in-line heater arranged such that a rail moves from the heater to the first forging position, and then to the second forging position along the same line. Such embodiments eliminate the need for manipulators to reorient the rail. As shown in, the embodiment requires no rotation of the rail work piece. Eliminating the need for rotating the work piece also saves time, and therefore reduces heat loss from the work piece.

With continuing reference to, a hydraulic forging press according to one embodimenthas a first pair of opposing side hydraulic cylindersa,b (b is out of view). A first top hydraulic cylinderis shown positioned above the first set of horizontal hydraulic cylindersa,b. Together, the horizontal hydraulic cylindersa,b and the top hydraulic cylinderform a first forging station, corresponding to a first forging position of a rail. The press further comprises a second pair of opposing side hydraulic cylindersa,b (b is out of view). A second top hydraulic cylinderis shown positioned above the second set of horizontal hydraulic cylindersa,b. Together, the second set of horizontal hydraulic cylindersa,b and the second top hydraulic cylinderform a second forging station, corresponding to a second forging position of a rail.

With regard to the second top hydraulic cylinder,shows that it is fitted with a movable die.

In another embodiment, the die is closed providing forging forces acting on all the surfaces of the rail simultaneously, and resulting in a dimensionally accurate product.

In another embodiment, pre-cutting an end portion of a rail through the foot and partway through the web provides structure suitable for receiving a clamp, which leads to improved straightness of the rail after forging.

In another embodiment, the induction heaterand the first and second forging stations are arranged such that a railcan be shifted in a line along the length of the railfrom the heaterto each station. The first forging station comprises horizontal hydraulic cylindersa,b, and vertical cylinder. The second station comprises horizontal cylindersa andb, and vertical cylinder. After carrying out a first forging operation at a the first station, vertical cylinderimpinges the horizontal die or die housing driven by horizontal cylindersa,b to disengage the die from the work piece, thus preventing lap formation. Then the partly forged railis shifted to the second forging station to carry out the next forging operation. The partially forged rails remain in this second location for subsequent forging operations on the rail foot involving the top cylinderand a linearly translatable top die. Unlike the first station, the second forging station includes a top diethat is linearly translatable along an axis in line with the rail. This allows different portions of the top die to engage a work piece by translating the top die along a linear axis.

With reference to, the second forging station comprises a rigid top frameand a rigid bottom frameconnected by four tie rodswith nutsat the top frameand the bottom frame. The top frameis fitted with a top cylinderhaving a piston rodfor a downward vertical stroke. A top die housingof the piston rodis linearly translatable between two working positions for progressive forging of the rail foot. The die housingis translated along an axis in line with the railusing hydraulic cylinders.

Turning to, the second stationof the rail forging presshas two horizontal side cylindersa,b mounted on suitable frames to provide horizontal force on the railfrom both sides. The side cylindersa,b are fitted with suitable diesas shown in. A hydraulically operated clamp(See(a), and(b)) is provided at one end to restrict sidewise bending of the rail.

In contrast to the first forging station, which consist of a pair of side cylinders,a andb, and a top cylinderhaving only a vertical axis of motion (), the second station comprises movable cylindersfor displacing the top diealong an axis in-line with the rail.

In another embodiment an induction heaterfor heating the railis mounted on a laterally movable stand, which for example and without limitation, may be hydraulically operated. The railis advanced fore and aft along a single translational axis using a servo motor-driven roller tablefitted with proximity switches for accurate linear positioning of the rail. The induction heatercan be moved inline between the railand the first and second forge stations when heating is required, and moved away when heating is complete. The railcan be accurately driven forward by the servo tableinto the induction heaterto a predetermined location. After reaching required temperature the railcan be driven aft by the roller table, withdrawing it from the induction heater. The induction heatercan then be laterally driven back to its home position. The railis again driven forward by the roller table, accurately positioning it inside the forge without the need for rotating the rail, or moving the railin any direction other than fore and aft.

A process according to an embodiment of the invention comprises the following steps. A 20 mm wide slotis cut 80 mm from one end of a rail to a height of 80 mm from the rail footas shown in. This forms end portion. Later in the process, the slotand end portionare used for clamping the railusing hydraulic clamp. Clamping in this manner keeps the railstraight during forging thereby preventing the rail from bending, which would result in rejection of the part. When forging is complete, the end portion can be cut off and discarded.

The process further includes the step of mounting the railto a movable servo-motor-controlled roller tablein an inverted orientation, with the head facing down (see e.g.). The table is equipped with elements for sensing the rail's position, such elements being well-known in the art, so that the table knows certain positions that are necessary for performing processes according to embodiments of the invention. Such positions including, without limitation, a position corresponding to the induction heater, a position corresponding to the first and second forging stations, and neutral home position outside of the heaterand the forge.

The process further includes the induction heaterbeing moved to a position in-line between the railand the forge. The roller tabledrives the railforward to a predetermined position corresponding to the interior of the induction heater, and the railis held in this position until a temperature reading indicates that the railis properly heated for forging, typically about 1180° C. The roller tablethen withdraws the rail, for example to the home position, and the induction heater is moved from between the railand the forge.

The process further includes the roller tabledriving the rail forward to a second predetermined position corresponding to the first forging station. Clampsandare applied to the railbeing forged thereby preventing lateral bending of the rail. With reference to, the first pair of horizontal hydraulic cylindersa,b laterally apply dieto the headof the railand to a section of the web. As shown in, the operation illustrated inresults in a symmetric rail headand causes the webto become thinner and taller. In, cylinderis shown in contact with dieto prevent movement that may cause lapping.

In, the dieis opened and add-on dieis placed in a forging position. In, the dieand add-on dieare then driven into the rail headand rail web, including a portion of the webnot accessible by the diealone. Add-on diesensure reaching a required web height without limiting reduction of the railweb. This helps to limit rejection of rails due to web over-thinning or lap formation. The dieis then opened again. The product of the forging operation illustrated inis a fully formed symmetric headand web; however, the footrequires further forging.

In an optional intermediate step, the railmay be reheated by withdrawing it using the roller table, and moving the induction heaterback to the inline position. The roller tablethen drives the railback into the induction heater, compensating for dissipated heat and bringing the rail back up to a forging temperature i.e., about 1150° C. The roller table then withdraws the railfrom the heaterand the heater is laterally moved back to its home position.

The railis advanced by the roller tableto the second forging station and clamped at three points with clamps,, and. With reference to, the horizontal dieis driven into the headand web. The top dieis shown in a first position over the rail foot. In the first position, a first portiona of the top dieis aligned with the foot. The first portiona includes a lateral steprunning the length of the first portiona. The lateral stepprovides a space for the footto laterally flow during forging. As shown in, the first portiona of the top dieis hydraulically driven downward into the foot, causing lateral flow. The top dieis then driven to a second position so that a second portionb of the top die is aligned with the foot. The stepis omitted from the second portionb, thus providing a flat die surface for the final step of forming the foot. The final forging operation is shown in, where the second portionb is hydraulically driven downward into the foot. Thus, the second portionb and the second set of horizontal diescooperate to form a geometrical profile of a finished symmetric rail section. All dies are then retracted and the railis withdrawn from the forge by roller table.

According to one embodiment the asymmetric rail forging press operations are controlled by a programmable logic controller having suitable safety interlocks. The forging process is operated through control desk equipped with a Supervisory Control and Data Acquisition (SCADA) system. Ample visualization and instrument data are displayed on the Human Machine Interface (HMI) screen.

According to one embodiment, a roller tableis adapted to receive a railroad rail, or similar work piece, and linearly position the rail along an axis. According to one embodiment, the rail may be inverted with the foot facing up and the head facing down; however, the invention is not limited to orientation. The roller tableis driven by a suitable means such as, without limitation, a servomotor. A starting position of the railmay be considered a “home” position, as illustrated in. The rail may be driven fore and aft by the servomotor as shown inalong an axis A. The embodiment includes a laterally movable induction heaterhaving at least two positionsA,B. A home positionA is off axis A, out of the linear path of the rail. A working positionB is on axis A, in line with the rail. Accordingly, the induction heater can be moved, by any suitable known means, into the working positionB and the rail can be driven a predetermined distance by the roller tablecorresponding to working positionB, and placing the railin inductive communication with the induction heater, as shown in. When the rail is inductively heated to a suitable forging temperature e.g., 1150° C., the railcan be withdrawn by the roller tableto a neutral position, e.g. as shown in, and the induction heatercan be moved to its home positionA.

The rail is then driven to a first forging station, as shown in. The first forging stationis in line with the roller tableon axis A and receives the railfrom the roller table. The stationincludes a first pair of opposing horizontal hydraulic cylindersa,b (see) having horizontal strokes. The hydraulic cylindersa,b include structure, such as die housings, receiving a first set of horizontal forging dies(). Accordingly, the cylindersa,b are adapted to drive the first set of horizontal forging dieshorizontally into a work piece to perform a forging operation. The first forging stationalso has a first top hydraulic cylinder(see) having a vertical stroke. The first top hydraulic cylinderis aligned to vertically impinge on the first set of horizontal forging diesduring a horizontal forging operation. As used here, impinging on the first set of horizontal diesalso includes impinging on a carrier or housing that holds the dies. Thus, the first top hydraulic cylinderholds the diesin place, or fixes their position, preventing movement that would otherwise cause defects in the work piece.

The first stationalso includes two clamps,for holding the railduring the forging operations. Suitable clamps are illustrated inand may be hydraulically driven. The clamps,are also shown in context in. Clampengages the rail at a cold section, meaning a portion of the rail that it is not heated to forging temperature and/or is not intended to engage a die during the forging operation. As used herein, the term “cold section” is synonymous with “unworked portion”. The length of rail between the clamps is referred to herein as a working section of the rail because it is the section being forged. Thus, the clamps,engage the rail at ends of a working section. Clampengages the leading end of the rail, which may be cut or otherwise prepared to receive the clamp. Thus, the hydraulic clamps,cooperate with the first top hydraulic cylinderto fix the orientation of the work piece during forging and especially to prevent bending of the work piece.

The first horizontal forging diesare shaped to form a closed die having the shape of the headand a portion of the webof a symmetric rail. When the dieis closed, i.e. pressed into the rail, the headis converted from asymmetric to symmetric and a portion of the webis thinned, increasing the height of the web. The balance of the web, and the foot, require further forging, which is handled in the next forging operation.

Regarding the next forging operation, add-on diesare translationally driven along axis A () from a home position to a working position. The add-on diesmay be driven from the home to the working position by any suitable known means, such as hydraulic means. Thus, the add-on diesare linearly translatable, parallel to the translational axis of the roller tableand axis A (). In the working position, the add-on diesare stacked vertically on the first set of horizontal forging dies (See.). Together the first set of horizontal diesand the add-on diescover the rail headand substantially the entire webof a symmetric rail. Thus, the diesandare shaped to form a closed die having the shape of the headand the full webof a symmetric rail when the diesandare pressed into the rail. In other words, the add-on diesand the first set of horizontal forging diescooperate to form part of the geometrical profile of a finished rail section including the head portion of the rail, a first section of the web portion of the rail contiguous with the head portion, and a second section of the web contiguous with the first portion. After the second forging operation, the dieand add-on dieare opened, and the railis driven by the roller tablealong axis A to the second forging station().

With continuing reference to, the railis driven to the second forging stationand clamped in three positions by clamps,, and. Specifically, the leading end of the rail is engaged by clamplocated in the second forging station, and clampsandengage the rail at their locations in the first forging station. A second set of horizontal forging diesare driven into the rail. The diesare pressed into the head and web portions of the rail, forming a closed die covering the entire geometric profile of the finished symmetric rail except the rail foot. Prior to closing the die, the headand webof the rail have already been converted to a symmetric form at the first forging station. The second set of horizontal diesmaintain the work piece in a correct form while conducting further forging operations on the foot.

With combined reference to, the second forging station() includes top hydraulic cylinder() having a vertical stroke and driving a top dieadapted to forge the foot. The top diehas two working positions corresponding to two different portionsa,b of the top die. The invention is not limited to top dieshaving first and second portionsa,b as described herein. Rather, two separate dies could be substituted without departing from the scope of the invention. A first portiona of the top dieis shown inhaving a lateral step. The lateral step runs the length of the first portiona. The purpose of the lateral stepis to provide space into which the footcan flow, forming bulge(). The bulgeis formed as the first portiona of the top die is pressed into the rail foot. Thus, the forging operation shifts the mass of the footlaterally so that the mass is centered over the web. The top die is then translationally driven by moveable cylinders() in a direction parallel axis A (see) such that the second portionb of the top dieis positioned over the work piece. As shown in, the second portionb is flat, omitting the lateral step. As the second portionb is pressed into the footby the top cylinder, the bulgecreated by the first portiona is flattened as shown in, thus forming the finished symmetric rail.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description only, they these are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously modifications remain possible, in particular from the point of view of the design of the various elements or by substitution of equivalent methods, without thus departing from the scope of protection of the invention.