Protecting device for processing tool of machine tool and honing machine

Abstract

This is to present a protecting device for processing tool of machine tool used in a machine tool of a type of machining such as grinding and cutting a work by rotating a processing tool mounted on a rotary spindle, for protecting the processing tool by preventing from damage or breakage due to excessive torque load. In a honing machine, for example, a magnetic coupling device ( 25 ) for transmitting the rotating force of a servo motor ( 16 ) to a rotary spindle ( 2 ) by magnetic action is provided between the rotary spindle ( 2 ) on which a honing tool ( 1 ) as processing tool is mounted and the servo motor ( 16 ) of a spindle rotation driving part ( 3 ) for rotating the rotary spindle ( 2 ), and the magnetic transmission torque of the magnetic coupling device ( 25 ) for transmitting the rotating force is set smaller than a specified torque load applied to the honing tool ( 1 ) (for example, breakage torque of honing tool ( 1 )). Accordingly, damage or breakage of the honing tool ( 1 ) by excessive torque load can be prevented effectively.

1 . A protecting device for processing tool of machine tool used in a machine tool of a type of machining such as grinding and cutting a work by rotating a processing tool mounted on a rotary spindle, for protecting the processing tool by preventing from damage or breakage,
 wherein magnetic coupling means for transmitting a rotating force of a rotation driving source to the rotary spindle by magnetic action is disposed between the rotary spindle and the rotation driving source for rotating this rotary spindle, and   the magnetic transmission torque for transmitting the rotating force of the magnetic coupling means is set smaller than the specified torque load applied to the honing tool.   
   
   
       2 . The protecting device for processing tool of machine tool of  claim 1 ,
 wherein the specified torque load is set smaller than the breakage torque for breaking the honing tool.   
   
   
       3 . The protecting device for processing tool of machine tool of  claim 1 ,
 wherein the magnetic coupling means is formed in a shape of annular magnet coupling coaxially disposed on the rotary spindle,   this annular magnet coupling has a driving side magnet ring member driven by and coupled to the rotation driving source side, and a driven side magnet ring member coupled to the rotary spindle side integrally in the rotating direction, and   the both magnet ring members are disposed parallel and concentrically opposite to each other without contacting with the annular magnet surface, and the magnetic transmission torque is set by a magnetic action gap formed between the two annular magnet surfaces.   
   
   
       4 . The protecting device for processing tool of machine tool of  claim 3 ,
 wherein the driving side and driven side magnet ring members are movable relatively in the axial direction of the rotary spindle, and the magnitude of the magnetic action gap between the annular magnet surfaces is changed, and the magnetic transmission torque is adjusted.   
   
   
       5 . The protecting device for processing tool of machine tool of  claim 4 ,
 wherein gap adjusting means is provided for adjusting the magnitude of the magnetic action gap by moving the driving side and driven side magnet ring members relatively in the axial direction to the rotary spindle,   this gap adjusting means has moving means for moving either one of the driving side and driven side magnet ring members in the axial direction of the rotary spindle, and gap control means for controlling this moving means, and   this gap control means is designed to control the moving means so that the magnetic transmission torque may be adjusted corresponding to the rotating speed of the rotary spindle.   
   
   
       6 . The protecting device for processing tool of machine tool of  claim 5 ,
 wherein the gap control means is configured to control the moving means so that the magnetic transmission torque may be a specified starting torque value until the rotary spindle reaches a specified rotating speed after starting from the stopped state, and that the magnetic transmission torque may be a specified processing torque when the rotating speed of the rotary spindle has reached the specified rotating speed.   
   
   
       7 . The protecting device for processing tool of machine tool of  claim 5 ,
 wherein the moving means has a feed screw mechanism coupled to either one of the driving side and driven side magnet ring members, and a rotation driving source for rotating and driving this feed screw mechanism, and   a nut member of this feed screw mechanism is coupled and fixed to either one of the driving side and driven side magnet ring members, and a screw member for moving back and forth this nut member is disposed parallel to the axial line of the rotary spindle.   
   
   
       8 . The protecting device for processing tool of machine tool of  claim 3 ,
 wherein the driving side and driven side magnet ring members have annular permanent magnets disposed at opposite sides of the ring member main body, so that the annular magnet surface is formed.   
   
   
       9 . The protecting device for processing tool of machine tool of  claim 3 ,
 wherein the driving side and driven side magnet ring members have at least one annular magnet row composed of permanent magnets disposed at equal intervals in the circumferential direction, at opposite sides of the ring member main body, and the annular magnet surface is formed of this annular magnet row.   
   
   
       10 . The protecting device for processing tool of machine tool of  claim 9 ,
 wherein a plurality of annular magnet rows different in array diameter are disposed concentrically on the opposite sides of the ring member main body.   
   
   
       11 . A honing machine comprising:
 a rotary spindle movable reciprocally in the axial line direction of the inner circumference of a work and rotatable about the axial line,   spindle rotating means for rotating and driving the rotary spindle about the axial line,   spindle reciprocal driving means for moving the rotary spindle reciprocally in the axial line direction of the inner circumference,   a honing tool disposed at the leading end of the rotary spindle and having an expanding and contracting honing grindstone having a grinding surface along the inner circumference,   grindstone feeding means for applying a specified feeding operation on the honing grindstone of this honing tool,   honing tool protecting means disposed in a driving transmission route of the rotary spindle and the spindle rotating means, for protecting the honing tool by preventing from damage or breakage, and   control means for controlling automatically by mutually interlocking the motions of the spindle rotating means, spindle reciprocal driving means, and grindstone feeding means,   wherein the honing tool protecting means is composed of the protecting device for processing tool of any one of  claims 1  to  10 .