Apparatus and process for producing blanks of rings or tubular members

Abstract

A process for producing bearing ring blanks, or gearwheel ring blanks or tubular connection-member blanks, comprises the steps of: •a) providing a steel tube; •b) dividing the tube into a plurality of slugs ( 30, 30 ′) each having an axial through cavity; •c) supplying the slugs ( 30, 30 ′) to a die assembly ( 20 ) of a cold-forming station, the forming station including a punch assembly ( 10 ); and •d) subjecting the slugs ( 30, 30 ′) to contained forward extrusion through the die assembly ( 20 ), wherein the thrust imparted by a pushing member ( 11 ) of the punch assembly ( 10 ) on a subsequent slug ( 30 ′) causes passage of a preceding slug ( 30 ) through the die assembly ( 20 ), with deformation thereof into a blank ( 40 ), while a restraining member ( 12 ) of the punch assembly ( 10 ) occupies the axial cavity of the subsequent slug ( 30 ′) and at least part of the axial cavity of the preceding slug ( 30 ).

1 . A process for producing blanks selected from among:
 rolling-bearing ring blanks,   gearwheel ring blanks,   tubular connection-members blanks, such as piston pins, bushings for catenaries, and bushings for vibration dampers,   the process comprising the steps of:   i) providing a tube made of steel,   ii) dividing the tube into a plurality of slugs each having an axial through hole;   iii) supplying the slugs to a die assembly of a cold-forming station, the cold-forming station also including a punch assembly;   iv) subjecting the slugs to contained forward extrusion through the die assembly, wherein a thrust imparted by a pushing member of the punch assembly on a subsequent slug causes passage of a preceding slug through an axial through cavity of the die assembly and cold deformation thereof into a blank, while a restraining member of the punch assembly occupies the axial through hole of the subsequent slug and at least part of the axial through hole of the preceding slug.   
     
     
         2 . The process according to  claim 1 , wherein the tube is a hot-rolled tube. 
     
     
         3 . The process according to  claim 1 , wherein one of the tube and the slugs is subjected to a phosphating process prior to step iii). 
     
     
         4 . The process according to  claim 1 , wherein the blanks are subjected to a levelling operation of at least one corresponding end face. 
     
     
         5 . The process according to  claim 1 , wherein step ii) is carried out in a separation station, in which the tube is subjected to one from among bench-shearing, cutting or shearing. 
     
     
         6 . The process according to  claim 1 , wherein step iii) comprises positioning individually each slug in a position corresponding to the axial through cavity of the die assembly by means of a manipulator or transfer system. 
     
     
         7 . The process according to  claim 6 , wherein:
 step ii) is carried out in a separation station, in which the tube is subjected to one from among bench-shearing, cutting or shearing; and   the manipulator or transfer system picks up a slug that has been separated in the separation station and transfers it in said position corresponding to the axial cavity of the die assembly in a manner synchronized with an actuation of the cold-forming station.   
     
     
         8 . The process according to  claim 1 , wherein steps iii) and iv) comprise the operations of:
 a) setting the preceding slug in a receiving region of the axial through cavity of the die assembly,   b) causing an axial approach between the punch assembly and the die assembly in such a way that:   b1) the pushing member causes a thrust on the preceding slug, at the start of said thrust a first part of an elongated-body portion of the restraining member extending in the axial through hole of the preceding slug and a second part of the elongated-body portion extending in an area-reducing region and a forming region of the axial through cavity of the die assembly,   b2) the pushing member subsequently pushes the preceding slug from the receiving region towards the forming region, passing through the area-reducing region,   wherein, at the end of said axial approach, the preceding slug has undergone deformation, with a respective upper part that engages the area-reducing region not occupied by the respective part of the elongated-body portion, and a respective lower part that engages at least one portion of the forming region not occupied by the respective part of the elongated-body portion;   c) causing an axial recession between the punch assembly and the die assembly;   d) setting the subsequent slug at the receiving region;   e) causing a further axial approach between the punch assembly and the die assembly in such a way that the pushing member forces the subsequent slug from the receiving region towards the forming region, with at least one part of the elongated-body portion of the restraining member that extends in the axial through hole of the subsequent slug, and another part of the elongated-body portion that engages at least partially the axial through hole of the preceding slug, the subsequent slug thus pushing the preceding slug so that also the upper part of the preceding slug passes through the forming region and wherein, at the end of said further axial approach, the subsequent slug has undergone deformation with a respective upper part that engages the area-reducing region not occupied by the respective part of the elongated-body portion, and a respective lower part that engages at least one portion of the forming region not occupied by the respective part of the elongated-body portion,   f) repeating operations c-e for an indefinite number of subsequent slugs.   
     
     
         9 . An apparatus for cold-forming of blanks selected from among:
 rolling-bearing ring blanks made of steel,   gearwheel ring blanks made of steel,   tubular connection-member blanks made of steel,   in particular blanks each having an axial through hole and an outer peripheral surface that extends between two opposite end faces of the blank, wherein the apparatus comprises:   a cold-forming station, having a punch assembly, a die assembly and an actuation system for translating the punch assembly and the die assembly with respect to one another in an axial direction, the die assembly having an axial through cavity and the punch assembly comprising a pushing member aligned axially to the axial through cavity of the die assembly;   a supply arrangement for supplying steel tubular slugs, in particular slugs each having an axial through hole and an outer peripheral surface, the supply arrangement being prearranged for supplying in an automated way to the cold-forming station one said tubular slug in a position corresponding to the axial through cavity of the die assembly,   a control system,   wherein the axial through cavity of the die assembly comprises:   a receiving region for receiving at least partially one said tubular slug, defined by a first surface portion of the axial through cavity that has a substantially cylindrical shape, the receiving region having a first diameter;   a forming region, defined by a second surface portion of the axial cavity that has a shape complementary to the outer profile of a blank to be obtained, the forming region having a minimum diameter smaller than the first diameter; and   an area-reducing region, which is axially comprised between the receiving region and the forming region, wherein the area-reducing region has an entry diameter corresponding to the first diameter of the receiving region and an exit diameter corresponding to the minimum diameter of the forming region,   wherein the pushing member of the punch assembly has an outer diameter slightly smaller than the first diameter of the receiving region and further comprises a restraining member, having an elongated-body portion that axially protrudes from an end face of the pushing member, substantially coaxial thereto, for engaging an axial through hole of one said tubular slug,   wherein the control system is prearranged for managing in a synchronized or coordinated way the actuation system of the cold-forming station and the supply arrangement of the steel tubular slugs, in such a way that, after positioning of at least one first tubular slug, or subsequent slug, in a position corresponding to the axial through cavity of the die assembly, the pushing member pushes said first tubular slug from the receiving region towards the forming region, with said first tubular slug that in turn urges an underlying second tubular slug, or preceding slug, to pass through the forming region, while the elongated-body portion of the restraining member extends through the axial through hole of the first tubular slug and at least part of the axial through hole of the second tubular slug.   
     
     
         10 . The apparatus according to  claim 9 , wherein the supply arrangement comprises a separation station, prearranged for dividing a tube into a plurality of said tubular slugs. 
     
     
         11 . The apparatus according to  claim 9 , wherein the supply arrangement comprises a manipulator or transfer system, for positioning individually each tubular slug in said position corresponding to the axial through cavity of the die assembly. 
     
     
         12 . The apparatus according to  claim 10 , wherein:
 the supply arrangement comprises a manipulator or transfer system, for positioning individually each tubular slug in said position corresponding to the axial through cavity of the die assembly; and   the manipulator or transfer system is prearranged for picking up one said tubular slug that has been separated in said separation station and transferring it into said position corresponding to the axial through cavity of the die assembly, in a way synchronized with actuation of the actuation system of the cold-forming station.   
     
     
         13 . The apparatus according to  claim 10 , wherein the supply arrangement comprises an advancement system, prearranged for advancing the tube towards the separation station. 
     
     
         14 . The apparatus according to  claim 9 , wherein the area-reducing region has a conical profile with an inclination indicatively comprised between 10° and 20°. 
     
     
         15 . A blank of a rolling-bearing ring, or a blank of a gearwheel ring, or a blank of a tubular connection member, obtained with the process according to  claim 1 . 
     
     
         16 . The process according to  claim 1 , wherein the steel is a bearing steel in case of production of rolling-bearing ring blanks or a case-hardening steels in case of production of gearwheel ring blanks or tubular connection-members blanks. 
     
     
         17 . The process according to  claim 1 , wherein step iv) is carried out on a press and step ii) is carried out in an apparatus being distinct from the press, between said apparatus and said press there being provided a system for transferring or loading the slugs on the press. 
     
     
         18 . The apparatus according to  claim 10 , comprising a press on which said cold-forming station is implemented, wherein the separation station is distinct from the press, between the separation station and the press there being provided a system for transferring or loading the slugs on the press. 
     
     
         19 . An apparatus for cold-forming of steel blanks each having an axial through hole and an outer peripheral surface that extends between two opposite end faces of the blank, wherein the apparatus comprises:
 a cold-forming station, having a punch assembly, a die assembly and an actuation system for translating the punch assembly and the die assembly with respect to one another in an axial direction, the die assembly having an axial through cavity and the punch assembly comprising a pushing member aligned axially to the axial through cavity of the die assembly;   a supply arrangement for supplying steel tubular slugs, in particular slugs each having an axial through hole and an outer peripheral surface, the supply arrangement being operable for supplying in an automated way to the cold-forming station one said tubular slug in a position corresponding to the axial through cavity of the die assembly,   a control system,   wherein the axial through cavity of the die assembly comprises:   a receiving region for receiving at least partially one said tubular slug, defined by a first surface portion of the axial through cavity that has a substantially cylindrical shape, the receiving region having a first diameter;   a forming region, defined by a second surface portion of the axial cavity that has a shape complementary to the outer profile of a blank to be obtained, the forming region having a minimum diameter smaller than the first diameter; and   an area-reducing region, which is axially comprised between the receiving region and the forming region, wherein the area-reducing region has an entry diameter corresponding to the first diameter of the receiving region and an exit diameter corresponding to the minimum diameter of the forming region,   wherein the pushing member of the punch assembly has an outer diameter slightly smaller than the first diameter of the receiving region and further comprises a restraining member, having an elongated-body portion that axially protrudes from an end face of the pushing member, substantially coaxial thereto, for engaging an axial through hole of one said tubular slug,   wherein the control system is operable for managing in a synchronized or coordinated way the actuation system of the cold-forming station and the supply arrangement of the steel tubular slugs, in such a way that, after positioning of at least one first tubular slug, or subsequent slug, in a position corresponding to the axial through cavity of the die assembly, the pushing member pushes said first tubular slug from the receiving region towards the forming region, with said first tubular slug that in turn urges an underlying second tubular slug, or preceding slug, to pass through the forming region, while the elongated-body portion of the restraining member extends through the axial through hole of the first tubular slug and at least part of the axial through hole of the second tubular slug,   wherein the supply arrangement comprises:
 a separation station, operable for dividing a tube into a plurality of said tubular slugs, 
 a manipulator system, for positioning individually each tubular slug in said position corresponding to the axial through cavity of the die assembly, and 
 an advancement system, operable for advancing the tube towards the separation station, and 
   wherein the manipulator system is operable for picking up one said tubular slug exiting said separation station and transferring it into said position corresponding to the axial through cavity of the die assembly, in a way synchronized with actuation of the actuation system of the cold-forming station.