Method and tools for manufacturing a master cylinder for a brake system, and cylinder manufactured therewith

Abstract

A method for manufacturing a master cylinder for a brake system, comprising a cylindrical main body, at least one flange integrally connected therewith, and a bore, extending in the cylindrical main body and through said at least one flange, wherein the master cylinder is manufactured by cold forging. Preferably the flange is cold forged by upsetting. Subsequently the cylindrical main body is provided with a bore. Said bore is realized in a series of forging steps, wherein at least the portion where the bore pierces the flange is executed in a separate step.

1 . A method for manufacturing a master cylinder for a brake system, comprising a cylindrical main body, at least one flange integrally connected therewith, and a bore, extending in the cylindrical main body and through said at least one flange, wherein the master cylinder is manufactured by cold forging.  
     
     
         2 . A method according to  claim 1 , wherein the cylinder is cold forged to its final desired shape in a series of consecutive steps, each step making use of a different set of forging tools.  
     
     
         3 . A method according to  claim 1  or  2 , wherein the cylinder is cold forged from a pressed, substantially massive slug, having a material volume that equals that of the cylinder to be manufactured, and an outer circumference, which substantially corresponds to the outer circumference of the cylindrical main body.  
     
     
         4 . A method according to any one of claims  1 - 3 , wherein the flange is cold forged first and subsequently the cylindrical main body is provided with the bore and extruded to its final, desired length.  
     
     
         5 . A method according to any one of claims  1 - 3 , wherein part of the cylindrical main body is cold forged at least partly concurrent with the flange.  
     
     
         6 . A method according to any one of the preceding claims, wherein the flange is cold forged in several consecutive steps.  
     
     
         7 . A method according to any one of the preceding claims, wherein the bore is cold forged in several consecutive steps.  
     
     
         8 . A method according to any one of the preceding claims, wherein the flange extends at some distance of each end of the cylindrical main body and the bore is cold forged in three consecutive steps, wherein during the first step a first portion of the bore is realised extending from one end of the main body up to the flange, during the second step a second portion of the bore is realised extending from the first portion to beyond the flange, thus piercing the flange and during the third step the bore is completed, ending at some distance from the opposite end of the cylindrical main body.  
     
     
         9 . A method according to any one of claims  3 - 8 , wherein the flange is cold forged by upsetting an end of the slug.  
     
     
         10 . A method according to  claim 9 , wherein a part of the cylindrical main body, which part extends beyond the flange, at a top side thereof, is forged at least partly together with the flange, by upsetting an end of the slug.  
     
     
         11 . A method according to any one of the claims  3 - 10 , wherein the slug prior to the first and/or a subsequent forging step is subjected to a treatment, enhancing the formability of the material, for instance a softening operation.  
     
     
         12 . A method according to any one of the claims  3 - 11 , wherein the slug is lubricated, preferably prior to each forging step.  
     
     
         13 . A method according to any one of the preceding claims, wherein the product, after having been cold forged, is subjected to a follow-up treatment, for instance annealing.  
     
     
         14 . A master cylinder for a brake system, substantially manufactured by cold forging, wherein the cylinder comprises an asymmetric, cylindrical main body and at least one flange integrally formed therewith, situated eccentric with respect to a mass centre line of the main body.  
     
     
         15 . A master cylinder according to  claim 14 , wherein the at least one flange extends substantially perpendicular to a centre line of the main body and is of non-rotation symmetric shape.  
     
     
         16 . A master cylinder according to  claim 14  or  15 , wherein the main body has at least two different cross sections along its length, at least one thereof having an asymmetric shape.  
     
     
         17 . A master cylinder according to any one of claims  14 - 16 , wherein the cylinder is made of aluminium or an aluminium alloy.  
     
     
         18 . A set of cold forging tools for use in a method according to any one of claims  1 - 13 .  
     
     
         19 . A set of cold forging tools according to  claim 18 , comprising at least one die and a series of mating punches, which punches can alternately cooperate with said at least one die during consecutive cold forging steps.