Process and device for notching a frame tube for an automobile vehicle seat, and more particularly a headrest support tube

Abstract

To make a notch in a tube, and more particularly a headrest support tube, with the notch featuring at least one locking edge perpendicular to the longitudinal direction (A) of the tube and forming a square angle with the external surface of the tube, the tube is gripped between clamping jaws, a punch is guided across the jaws in a working direction (B) that converges with the axis (A) of the tube and is angled with respect to said axis by a working angle (α 1 ) of between approximately 15° and approximately 45°. The tip of the punch features a tooth with a working face, an angled rear face, and a front face joining the working face to the rear face, with the working face and the front face forming a working edge, and a suitable punching force is applied to the punch to make the tooth penetrate the tube wall in said working direction, until said working edge has penetrated the tube by a radial distance equal to the depth of the notch to be produced.

1 . Process for notching a support tube ( 1 ) for an automobile vehicle seat, and more particularly a headrest support tube, by which at least one notch ( 12 ) is made in the tube, this notch featuring at least one locking edge ( 13 ) perpendicular to the longitudinal direction (A) of the tube and forming a sharp edge with the external surface of the tube, 
 characterized in that: 
 the tube ( 1 ) is gripped in the area surrounding the notch to be formed between clamping jaws ( 51 ,  52 ) defining a cylindrical clamping surface ( 53 ,  54 ) enclosing the periphery of the tube,  
 a punch ( 6 ) is guided across the jaws in a working direction (B) that converges with the axis (A) of the clamping surface and is angled with respect to the said axis at a predetermined working angle (α 1 ) of between approximately 15° and 45°, with the tip ( 63 ) of the punch featuring a notch forming tooth ( 21 ) with a working face ( 22 ) parallel to the locking edge of the notch to be made, a rear face ( 24 ) that extends along a plane inclined with respect to the tube axis, and a front face ( 23 ) joining the working face and the rear face, with the intersection between the working face and the front face forming a working edge ( 25 ),  
 and a punching force is applied to the punch such that the tooth ( 21 ) penetrates the tube wall in the said working direction until the working edge has penetrated the tube by a radial distance equal to the depth of the notch to be produced.  
   
     
     
         2 . Process in accordance with  claim 1 , characterized in that the working angle (α 1 ) is between 30° and 40°.  
     
     
         3 . Process in accordance with  claim 1 , characterized in that the angle (α 3 ) of the rear face ( 24 ) with respect to the said working direction (B) is between  0 ° and the said working angle (α 1 ).  
     
     
         4 . Process in accordance with  claim 1 , characterized in that to make a notch ( 18 ) featuring two square edges, the notch forming operations are repeated by reversing the working angle symmetrically with respect to a plane orthogonal to the tube axis, and such that in the second operation the front face ( 23 ) of the tooth reaches the bottom of the notch ( 18 ) formed by the front face during the first forming operation.  
     
     
         5 . Process in accordance with  claim 4 , characterized in that the forming of the notch bottom is finished using a punch ( 33 ) that moves perpendicularly to the tube axis and whose end face profile corresponds to the desired form of the bottom of the notch ( 18 ).  
     
     
         6 . Device for notching a support tube for an automobile vehicle seat, and more particularly a headrest support tube, characterized in that it comprises: 
 clamping jaws ( 51 ,  52 ) defining a cylindrical clamping surface ( 53 ,  54 ) enclosing the periphery of the tube ( 1 ), to grip the tube in the area surrounding the notch ( 12 ) to be made,    a punch ( 6 ) guided across the jaws in a working direction (B) that converges with the axis (A) of the clamping surface and is angled with respect to the said axis at a predetermined working angle (α 1 ) of between 15° and 45°, with the tip of the punch featuring a notch forming tooth ( 21 ) with a working face ( 22 ) parallel to the locking edge of the notch to be made, a rear face ( 24 ) that extends along a plane inclined with respect to the tube axis, and a front face ( 23 ) joining the working face and the rear face, with the intersection between the working face and the front face forming a working edge ( 25 ),    control means ( 42 ) to apply a suitable punching force to punch ( 6 ) to make tooth ( 21 ) penetrate the tube wall in the said working direction.    
     
     
         7 . Device in accordance with  claim 6 , characterized in that the working face ( 22 ) of the tooth ( 21 ) of the punch ( 6 ) forms an angle (α 2 ) of between 70 and 100° with the axis (A) of the clamping surface ( 53 ,  54 ).  
     
     
         8 . Device in accordance with  claim 6 , characterized in that the rear face ( 24 ) of the tooth ( 21 ) of the punch ( 6 ) forms an angle of between 0° and the value of the working angle (α 1 ) with the axis (A) of the clamping surface.  
     
     
         9 . Device in accordance with  claim 6 , characterized in that the clamping jaws comprise a fixed jaw ( 52 ) and a moving jaw ( 51 ) perpendicular to the axis (A) of the tube and controlled by a clamping actuator ( 43 ).  
     
     
         10 . Device in accordance with  claim 9 , characterized in that one of the jaws is made in contiguous two sections ( 52   a,    52   b ) and features a hole to guide the punch ( 6 ), formed by the combination of two grooves ( 56 ) made in the two sections of the jaw, in the joining plane ( 55 ) between the said two parts.  
     
     
         11 . Device in accordance with  claim 10 , characterized in that the tooth ( 21 ) protrudes with respect to an end face ( 64 ) of the punch, the said end face meeting the clamping surface at a tangent when the punch reaches end of travel after the drawing operation.  
     
     
         12 . Device in accordance with  claim 11 , characterized in that the end face ( 64 ) has a concave profile corresponding to the clamping surface.  
     
     
         13 . Support tube ( 1 ) for an automobile vehicle seat, and more particularly a headrest frame tube, characterized in that it is provided with sharp angle notches ( 12 ) obtained by the process in accordance with one of  claims 1  to  5 , without removing material and without deforming the external cross-section of the tube.