Method for manufacturing a camshaft

Abstract

A method of manufacturing a camshaft for an engine having cylinder head bolts, includes providing a tube, placing at least one separately produced cam in a position on the tube along an axis of the tube, fastening the cam to the tube and pressing at least one external indentation into the tube at a part of the circumference of the tube. The indentation is pressed transversely toward the tube axis into inner and outer surfaces of a wall thickness of the tube at an axial location along the tube axis and does not encircle the tube. The indentation is also disposed along the tube and beside the cam with no part of the indentation being covered by the cam and the indentation being sufficiently deep to allow access to the cylinder head bolts of the engine.

1 . A method for manufacturing a camshaft comprising: providing a tube having a tube wall with a wall thickness and an inner and outer surface, and pressing at least one indentation radially into the tube wall.  
   
   
       2 . A method as claimed in  claim 1 , including pressing a plurality of said indentations into the tube wall, said indentations being aligned along a longitudinal direction of the tube, parallel to an axis of the tube.  
   
   
       3 . A method as claimed in  claim 2 , including pressing each indentation into the tube wall individually, one after the other.  
   
   
       4 . A method as claimed in  claim 2 , including pressing the indentations into the tube wall simultaneously.  
   
   
       5 . A method as claimed in  claim 1 , including pressing the indentation when the tube is cold.  
   
   
       6 . A method as claimed in  claim 1 , including pressing the indentation when the tube is hot.  
   
   
       7 . A method as claimed in  claim 1 , wherein for the tube is of metal.  
   
   
       8 . A method as claimed in  claim 1 , wherein the tube is made of at least one of steel St52, or aluminum, or alloys thereof.  
   
   
       9 . A method as claimed in claims  1 , including clamping the tube into a bottom die for encompassing the tube, and pressing the indentation into the tube wall using a stamp that is pressed through an opening in the bottom die and against the tube to form the indentation to have a selected depth.  
   
   
       10 . A method as claimed in  claim 9 , wherein the bottom die is separated along the tube into at least two parts.  
   
   
       11 . A method as claimed in  claim 9 , wherein the bottom die receives the tube in a form-fittingly manner with a dimensional tolerance between an outer tube diameter (d) and the bottom die of ±5% at most.  
   
   
       12 . A method as claimed in  claim 2 , including using a removable bottom die to engage the tube, for each indentation to be pressed.  
   
   
       13 . A method as claimed in  claim 2 , including engaging a plurality of cams onto the tube, and fixing each cam at a selected position on the tube that is spaced from all of the indentations in the tube.  
   
   
       14 . A method of manufacturing a camshaft for an engine having cylinder head bolts, comprising: providing a tube; placing at least one separately produced cam in a position on the tube along an axis of the tube; fastening the cam to the tube; pressing at least one external indentation into the tube at a part of the circumference of the tube, the indentation being pressed transversely toward the tube axis into inner and outer surfaces of a wall thickness of the tube at an axial location along the tube axis, and not encircling the tube, the indentation being disposed along the tube and beside the cam with no part of the indentation being covered by the cam and the indentation being sufficiently deep to allow access to the cylinder head bolts of the engine.  
   
   
       15 . A method as claimed in  claim 14 , wherein, in a region of deformation of the pressed-in indentation an outer wall of the tube does not project beyond a selected original tube diameter.  
   
   
       16 . A method as claimed in  claim 14 , wherein several indentations are pressed into the tube and are aligned in a longitudinal direction of the tube, parallel to the tube axis.  
   
   
       17 . A method as claimed in  claim 14 , wherein the indentation has a depth of up to 40% of the outer tube diameter and the indentation is disposed transversely to the axial direction.  
   
   
       18 . A method as claimed in  claim 14 , wherein the tube comprises a metal.  
   
   
       19 . A method as claimed in  claim 18 , wherein the tube is steel St52 and/or aluminum or its alloys.  
   
   
       20 . A method for manufacturing a camshaft tube for an engine having cylinder head bolts, comprising: providing a tube; placing at least one of cams and bearings on the tube at selected positions; fastening the at least one of cams and bearings along the tube axis; pressing into the tube, a plurality of external indentations that are pressed transversely to the tube axis into inner and outer surfaces of a wall thickness of the tube and not encircling the tube and with a single indentation at each location along the tube axis, said indentations being disposed along the tube and beside the cams or bearings corresponding to a desired position where access to the cylinder head bolts in an installed state is required with no part of the indentations being covered by the cams or bearings and the indentations each being sufficiently deep to allow access to the cylinder head bolts of the engine.  
   
   
       21 . A method of manufacturing a camshaft for an engine having cylinder head bolts, comprising: providing a tube; pressing at least one external indentation into the tube at a part of the circumference of the tube, the indentation being pressed transversely toward the tube axis into inner and outer surfaces of a wall thickness of the tube at an axial location along the tube axis, and not encircling the tube; placing at least one separately produced cam in a position on the tube along an axis of the tube; fastening the cam to the tube; the indentation being disposed along the tube and beside the cam with no part of the indentation being covered by the cam and the indentation being sufficiently deep to allow access to the cylinder head bolts of the engine.  
   
   
       22 . A method for manufacturing a camshaft tube for an engine having cylinder head bolts, comprising: providing a tube; pressing into the tube, a plurality of external indentations that are pressed transversely to the tube axis into inner and outer surfaces of a wall thickness of the tube and not encircling the tube and with a single indentation at each location along the tube axis; placing at least one of cams and bearings on the tube at selected positions; fastening the at least one of cams and bearings along the tube axis; said indentations being disposed along the tube and beside the cams or bearings corresponding to a desired position where access to the cylinder head bolts in an installed state is required with no part of the indentations being covered by the cams or bearings and the indentations each being sufficiently deep to allow access to the cylinder head bolts of the engine.