Metal 3d printer

Abstract

A metal 3-D printer includes a powder layer formation device having a blade for planarizing metal powder, a table driving device lowering a table by a predetermined lowering distance in anticipation of a formation of a powder layer, a laser irradiating device irradiating a laser beam at the powder layer to form a sintered layer having a predetermined upper surface region, a numerical control apparatus controlling the powder layer formation device, the table driving device, the laser irradiating device and a machining apparatus. When the blade collides with an obstacle formed on an upper most sintered layer, an end mill is lowered according to a predetermined lowering distance such that a lower end of the end mill is lower than an upper surface of the powder layer, and moves the end mill across a predetermined upper surface region of the uppermost sintered layer to remove the obstacle.

What is claimed is: 
     
         1 . A metal 3-D printer, comprising:
 a table, movable in a vertical direction;   a powder layer formation device, comprising at least one blade for planarizing metal powder, and moving the at least one blade in a horizontal axis direction to form a powder layer on the table;   a table driving device, lowering the table by a predetermined lowering distance in anticipation of a formation of the powder layer;   a laser irradiating device, irradiating a laser beam at the powder layer to form a sintered layer having a predetermined upper surface region;   a machining apparatus, having a cutting tool, and moving the cutting tool; and   a numerical control apparatus, controlling the powder layer formation device, the table driving device, the laser irradiating device and the machining apparatus, the numerical control apparatus comprising:
 a memory which stores the predetermined lowering distance and the predetermined upper surface region; and 
 a collision detector, generating a detection signal representing the at least one blade has collided with an obstacle formed on an upper most sintered layer, 
   wherein, in response to the detection signal of the collision detector, the metal 3-D printer lowers the cutting tool according to the predetermined lowering distance such that a lower end of the cutting tool is lower than an upper surface of the powder layer, and moves the cutting tool across the predetermined upper surface region of the uppermost sintered layer to remove the obstacle.   
     
     
         2 . The metal 3-D printer as claimed in  claim 1 , wherein the cutting tool is a rotating end mill. 
     
     
         3 . The metal 3-D printer as claimed in  claim 1 , wherein the powder layer formation device has a servo motor for moving the at least one blade, and the collision detector generates the detection signal when a current supplied to the servo motor increases and exceeds a set value. 
     
     
         4 . The metal 3-D printer as claimed in  claim 1 , wherein, in response to the detection signal of the collision detector, the numerical control apparatus lowers the cutting tool such that the lower end of the cutting tool is lower than the upper surface of the powder layer by the predetermined lowering distance. 
     
     
         5 . The metal 3-D printer as claimed in  claim 1 , wherein data representing a correction distance is stored in the memory, and in response to the detection signal of the collision detector, the numerical control apparatus lowers the cutting tool such that the lower end of the cutting tool is lower than the upper surface of the powder by a distance which is the correction distance added to the predetermined lowering distance. 
     
     
         6 . The metal 3-D printer as claimed in  claim 5 , wherein the cutting tool is a rotating end mill. 
     
     
         7 . The metal 3-D printer as claimed in  claim 5 , wherein the powder layer formation device has a servo motor for moving the at least one blade, and the collision detector generates the detection signal when a current supplied to the servo motor increases and exceeds a set value. 
     
     
         8 . The metal 3-D printer as claimed in  claim 5 , wherein the correction distance is a negative value. 
     
     
         9 . The metal 3-D printer as claimed in  claim 5 , wherein, when the powder layer formation device is forming the powder layer, the numerical control apparatus moves the cutting tool to a retracted position such that the lower end of the cutting tool is higher than the upper surface of the powder layer by a predetermined height, and in response to the detection signal of the collision detector, the numerical control apparatus lowers the cutting tool from the retracted position by a distance which is the predetermined height and the correction distance added to the predetermined lowering distance.