Machining a workpiece in a turret lathe and an NC lathe therefor

Abstract

.[.A method of.]. .Iadd.Apparatus for .Iaddend.machining a workpiece, which is rotatable about a first axis, by a tool pivotable about a second axis parallel to the first axis and drivable about a third axis perpendicular to the second axis. To allow the circumference of the workpiece to be machined off-center without the necessity of moving the first or the second axis transversely to the plane defined by these two axes, the workpiece and the tool are rotated or pivoted about the first .[.or.]. .Iadd.and .Iaddend.second .[.axis.]. .Iadd.axes.Iaddend., respectively, at the same time, in the same direction and at the same angular velocity and, simultaneously the second axis is displaced transversely to the first axis at such a velocity that the equation X 2 =Y 2 +A 2 always applies, wherein X is the distance of the second axis from the first axis, Y is the distance of the first axis from the plane defined by the second and third axes and A is the distance of the second axis from the vertical projection of the first axis on this plane.

What is claimed is: 
     
       1. In an NC lathe, comprising a main spindle mounted for rotation in a spindle stock about a main spindle axis; a main motor for rotatably driving said main spindle about said main spindle axis; a workpiece chuck means mounted on said main spindle; a tool turret arranged adjacent said main spindle; means for rotatably mounting said tool turret; means for rotatably driving said tool turret about a tool turret axis parallel to the main spindle axis; said tool turret comprising a turret body and at least one turret spindle for holding a tool rotatably mounted in said turret body; means for rotatably driving said turret spindle about a turret spindle axis extending radially to the turret axis; a carriage bearing said tool turret for slidable displacement transversely to the main spindle axis, and a carriage drive for slidably displacing said carriage, the improvement comprising NC control means operatively connected to said main motor, the tool turret driving means, and said carriage drive for effecting controlled, stepless, transverse displacement of the carriage and controlled stepless rotation of the main spindle and of the tool turret such that simultaneously (a) the main spindle is rotated about the main spindle axis in a defined direction of rotation and with a defined angular velocity of dγ/dt;   (b) the turret spindle is rotated about the turret spindle axis;   (c) the turret is rotated about the turret axis in the defined direction of rotation and with said defined angular velocity;   (d) the carriage is displaced transversely to the main spindle axis at a velocity dX/dt said velocities being the first derivatives of the following equations: ##EQU3## wherein t, γ, X, A, Y o , and v y  denote the following: t=the time which is equal to zero when a tool carried by said turret spindle touches a workpiece carried by said chuck means for the first time;     γ=the angle between the turret spindle axis and a first plane defined by the main spindle axis and the turret axis;   X=the distance of the turret axis from the main spindle axis;   A=the distance of the turret axis from the normal projection of the main spindle axis onto a second plane defined by the turret axis and the turret spindle axis, which plane pivots about the turret axis;   Y=the distance of the main spindle axis from said second plant, with Y o  being the value of Y when t equals zero;   v y  =the feed velocity dy/dt of the turret spindle axis relative to the main spindle axis in the direction of diminishing values of Y.   
     
     
       2. In an NC lathe, comprising a main spindle mounted for rotation in a spindle stock about a main spindle axis; a main motor for rotatably driving said main spindle about said main spindle axis; a workpiece chuck means mounted on said main spindle; a tool turret arranged adjacent said main spindle; means for rotatably mounting said tool turret; means for rotatably driving said tool turret about a tool turret axis parallel to the main spindle axis; said tool turret comprising a turret body and at least one turret spindle for holding a tool rotatably mounted in said turret body; means for rotatably driving said turret spindle about a turret spindle axis extending radially to the turret axis; a carriage bearing said tool turret for slidable displacement transversely to the main spindle axis, and a carriage drive for slidably displacing said carriage, the improvement comprising NC control means operatively connected to said main motor, the tool turret driving means and said carriage drive for effecting controlled stepless transverse displacement of the carriage and controlled stepless rotation of the main spindle and of the tool turret such that simultaneously (a) the main spindle is rotated about the main spindle axis in a defined direction of rotation and with a defined angular velocity dγ/dt;   (b) a turret spindle is rotated about the turret spindle axis;   (c) the turret is rotated about the turret axis in the defined direction of rotation and with said defined angular velocity;   (d) the carriage is displaced transversely to the main spindle axis at a velocity dX/dt said velocities being the first derivatives of the following equations: ##EQU4## wherein t, .Iadd.γ, .Iaddend.X, Y, A o , and v A  denote the following:     t=the time which is equal to zero when a tool carried by the turret spindle touches a workpiece carried by said chuck means for the first time;   γ=the angle between the turret spindle axis and a first .[.plant.]. .Iadd.plane .Iaddend.defined by the main spindle axis and the turret axis;   X=the distance of the turret axis from the main spindle axis;   A=the distance of the turret axis from the normal projection of the main spindle axis onto a second plane defined by the turret axis and the turret spindle axis, which plane pivots about the turret axis, with A o  being the value of A when t equals zero;   Y=the distance of the main spindle axis from said second plane;   V A  =the feed velocity dA/dt of the turret body relative to the main spindle in the direction of diminishing values of A.   
     
     
       3. The lathe of claim 1 .[.or 2.]., .Iadd.2, 15, 19 or 23 .Iaddend.in combination with a C-axis motor controlled by said NC control means, and an angular position transducer connected to the main spindle is provided for controlled drive of the main spindle with respect to its angle of rotation. 
     
     
       4. The lathe of claim 3, wherein an actuatable coupling connects the C-axis motor to the main spindle. 
     
     
       5. The lathe as defined in claim 4, wherein the C-axis motor is the turret indexing motor. 
     
     
       6. The lathe as defined in claim 5, in which an actuatable coupling is provided between the main spindle and the tool turret, and an actuatable blocking device is associated with the tool turret for stopping said tool turret. 
     
     
       7. The lathe of claim 5, in combination with a first gear wheel in drive connection with the main spindle and mounted on an axis which is stationary relative to the main spindle axis, and a second gear wheel in drive connection with the tool turret mounted on an axis which is stationary in relation to the turret axis and parallel to the axis of the first gear wheel; a gear unit arranged between said first and second gear wheels comprising a freely movable intermediate shaft extending parallel to the axes of the first and second gear wheels; third and fourth gear wheels mounted for rotation with the intermediate shaft; a pair of continuous interconnecting means, a first of which engages the first and third gear wheels and a second of which engages the second and fourth gear wheels; a pair of connecting arms extending between said wheel axes and said intermediate shaft; a first arm being pivotable about both the axis of the first gear wheel as well as the intermediate shaft, and a second arm being pivotable about both the intermediate shaft and the axis of the second gear wheel. 
     
     
       8. The lathe has defined in claim 7, in which the first and third gear wheels are of the same size and the second and fourth gear wheels are of the same size. 
     
     
       9. The lathe as defined in claim 7, in which the arms are adjustable with respect to their length. 
     
     
       10. The lathe as defined in claim .[.5.]. .Iadd.9.Iaddend., in which the first and third gear wheels are of the same size and the second and fourth gear wheels are of the same size. 
     
     
       11. The lathe as defined in claim 1 or 2, in which the main motor is stationary, and a gear unit connects .[.the.]. .Iadd.said .Iaddend.main motor to a turret spindle drive shaft concentric to the turret axis; said gear unit comprising a first gear wheel with a stationary axis, a second gear wheel, the axis of which is stationary in relation to the turret axis and parallel to the axis of the first gear wheel; a freely movable intermediate shaft parallel to the axes of the first and second gear wheels; said gear unit also comprising third and fourth gear wheels nonrotatably connected to the intermediate shaft and a pair of continuous connecting means, a first of which runs over the first and third gear wheels and a second of which runs over the second and fourth gear wheels; and a first arm pivotable about the axis of the first gear wheel and the intermediate shaft for interconnecting said .[.axes.]. .Iadd.axis .Iaddend.and said intermediate shaft, and a second arm pivotable about the intermediate shaft and the axis of the second gear wheel for interconnecting said intermediate shaft and .Iadd.the axis of said .Iaddend.second gear wheel. 
     
     
       12. The lathe has defined in claim 11 in which the arms are adjustable with respect to their length. 
     
     
       13. The lathe as defined in claim 12, in which the first and third gear wheels are of the same size and the second and fourth gear wheels are of the same size. 
     
     
       14. The lathe as defined in claim 11, in which the first and third gear wheels are of the same size and the second and fourth gear wheels are of the same size. .Iadd. 
     
     
       15.  In an NC lathe including a main spindle mounted for rotation in a spindle stock about a main spindle axis; motor means for rotatably driving said main spindle about said main spindle axis; a workpiece chuck means mounted on said main spindle; a tool turret arranged adjacent said main spindle; means for rotatably mounting said tool turret; means for rotatably displacing said tool turret about a tool turret axis parallel to the main spindle axis; said tool turret comprising a turret body and at least one turret spindle for holding a tool rotatably mounted in said turret body; means for rotatably driving said turret spindle about a turret spindle axis disposed in a plane perpendicular to the tool turret axis; slidable carriage means and a carriage drive for effecting relative displacement between said tool turret and said main spindle in a direction transverse to the axes thereof, the improvement comprising: NC control means operatively connected to said motor means, the means for rotatably displacing said tool turret and said carriage drive for effecting controlled, stepless, transverse displacement of the carriage and controlled stepless rotational displacements of simultaneously, during machining by said lathe: (a) said main spindle is displaced about said main spindle axis in a defined direction of rotation to provide predetermined continuous angular displacement of said main spindle and said chuck means;   (b) said turret spindle is rotated about said turret spindle axis;   (c) said tool turret is displaced about said tool turret axis in said defined direction of rotation and with the same continuous angular displacement as said main spindle and said chuck means, whereby said turret spindle axis is maintained perpendicular to a predetermined plane parallel to said main spindle axis and rotating with said workpiece chuck means during such rotational displacement of said main spindle and said tool turret; and   (d) said relative displacement is effected between said tool turret and said main spindle in a direction transverse to the main spindle axis to effect relative positioning of said turret spindle in a direction parallel to the first spindle axis and thus perpendicular to said predetermined plane in a predetermined manner while performing such machining..Iaddend. .Iadd.   
     
     
       16.  The lathe as defined in claim 15, wherein said turret spindle axis intersects and extends radially from said tool turret axis..Iaddend. .Iadd.17. The lathe as defined in claim 15, wherein said tool turret is mounted on said carriage..Iaddend. .Iadd.18. The lathe as defined in claim 15, wherein said NC control means includes means for effecting rotational displacement of said main spindle and said tool turret at the same constant angular velocity during machining operation by said 
     
     
        lathe..Iaddend. .Iadd.19.  In an NC lathe including a main spindle mounted for rotation in a spindle stock about a main spindle axis; motor means for rotatably driving said main spindle about said main spindle axis; a workpiece chuck means mounted on said main spindle; a tool turret arranged adjacent said main spindle; means for rotatably mounting said tool turret; means for rotatably displacing said tool turret about a tool turret axis parallel to the main spindle axis; said tool turret comprising a turret body and at least one turret spindle for holding a tool rotatably mounted in said turret body; means for rotatably driving said turret spindle about a turret spindle axis disposed in a plane perpendicular to the tool turret axis; slidable carriage means and a carriage drive for effecting relative displacement between said tool turret and said main spindle in a direction transverse to the axes thereof, the improvement comprising: NC control means operatively connected to said motor means, the means for rotatably displacing said tool turret, and said carriage drive for effecting controlled, stepless, transverse displacement of the carriage and controlled stepless rotational displacements of the main spindle and of the tool turret such that simultaneously, during machining by said lathe: (a) said main spindle is displaced about said main spindle axis in a defined direction of rotation and with a defined angular velocity;   (b) said turret spindle is rotated about said turret spindle axis;   (c) said tool turret is displaced about said tool turret axis in said defined direction of rotation and with said defined angular velocity whereby said turret spindle axis is maintained perpendicular to a predetermined plane parallel to said main spindle axis and rotating with said workpiece chuck means during such rotational displacement of said main spindle and said tool turret; and   (d) said carriage is displaced in a direction transverse to the main spindle axis at a displacement velocity to effect relative positioning of said turret spindle in a direction parallel to the turret spindle axis and thus perpendicular to said predetermined plane in a predetermined manner   
     
     
        while performing such machining..Iaddend. .Iadd.20.  The lathe as defined in claim 19, wherein said turret spindle axis intersects and extends radially from said tool turret axis..Iaddend. .Iadd.21. The lathe as defined in claim 20, wherein said tool turret is mounted on said 
     
     
        carriage..Iaddend. .Iadd.22.  The lathe as defined in claim 15 or 19 in which the motor means is stationary, and a gear unit connects said motor means to a turret spindle drive shaft concentric to the turret axis; said gear unit comprising a first gear wheel with a stationary axis, a second gear wheel, the axis of which is stationary in relation to the turret axis and parallel to the axis of the first gear wheel; a freely movable intermediate shaft parallel to the axes of the first and second gear wheels; said gear unit also comprising third and fourth gear wheels nonrotatably connected to the intermediate shaft and a pair of continuous connecting means, a first of which runs over the first and third gear wheels and a second of which runs over the second and fourth gear wheels; and a first arm pivotable about the axis of the first gear wheel and the intermediate shaft for interconnecting said axis and said intermediate shaft, and a second arm pivotable about the intermediate shaft and the axis of the second gear wheel for interconnecting said intermediate shaft 
     
     
        and the axis of said second gear wheel..Iaddend. .Iadd.23.  An NC lathe including a spindle stock; a main spindle mounted for rotation in said spindle stock about a main spindle axis;   a workpiece chuck means mounted on said main spindle;   driving means for rotatably displacing said main spindle about said main spindle axis;   NC control means operatively connected to said driving means for effecting controlled rotational displacement of said main spindle in a defined direction about said main spindle axis during machining operation of said lathe;   a rotatable tool turret arranged adjacent said main spindle;   means for rotatably displacing said tool turret about a tool turret axis parallel to said main spindle axis;   said tool turret comprising a turret body, at least one turret spindle and means for holding a tool in said spindle for rotation about a turret spindle axis disposed in a plane extending generally normal to said tool turret axis;   a drive for rotating said turret spindle about said turret spindle axis to effect such machining operation;   means for controlling said tool turret displacing means and for thereby effecting controlled rotational displacement of said turret spindle axis in said defined direction about said tool turret axis simultaneously with and with the same rotational displacement as said main spindle during such machining operation whereby said turret spindle axis is maintained perpendicular to a predetermined plane which is parallel to said main spindle axis and rotating with said workpiece chuck means during such machining; and   carriage means and a carriage drive associated with said tool turret and said main spindle and responsive to said NC control means for effecting controlled, stepless, relative displacement between said tool turret and said main spindle in a direction transverse to said main spindle axis to position a tool mounted in said tool holding means of said turret spindle in a direction along said tool spindle axis in a predetermined manner simultaneously with such rotational displacement of said turret spindle axis and main spindle during such machining of a workpiece in said chuck by said tool,   whereby off-center machining may be performed by said lathe without a feed motion of the tool turret relative to said workpiece chuck in a direction generally normal to said direction of relative displacement between said tool turret and said main spindle..Iaddend. .Iadd.24. A lathe as defined in claim 23, including transducer means for providing an output in accordance with the angular position of said main spindle, and wherein said NC control means is responsive to the output of said transducer for effecting such controlled rotational displacement of said main spindle in said defined direction during such machining of a workpiece by said   
     
     
        machine..Iaddend. .Iadd.25.  A lathe as defined in claim 23, wherein said tool turret is mounted on said carriage means..Iaddend. .Iadd.26. A lathe as defined in claim 23, 24 or 25 wherein said turret spindle is disposed in said tool turret such that said turret spindle axis intersects and extends radially from said tool turret axis..Iaddend. .Iadd.27. A lathe as defined in claim 23, wherein said means for rotatably displacing said tool turret and said means for controlling said means for rotatably displacing said tool turret includes an actuable mechanical coupling between said main spindle and said tool turret..Iaddend. .Iadd.28. A lathe as defined in claim 23, wherein said means for controlling said means for rotatably 
     
     
        displacing said tool turret includes said NC control means..Iaddend. 29. A lathe as defined in claim 23, wherein said means for rotatably displacing said tool turret is a motor, and said means for controlling said tool turret displacing means includes transducer means for providing an output in accordance with the angular position of said tool turret and said NC control means being responsive to the output of said transducer means for effecting such controlled rotational displacement of said turret spindle axis.