NUMERICAL CONTROLLER HAVING SPEED CONTROL FUNCTION FOR MULTI-AXIS MACHINING DEVICE

• US 20120221141A1
• Filed: 11/01/2011
• Published: 08/30/2012
• Est. Priority Date: 02/25/2011
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Otsuki, Toshiaki, Sasaki, Takafumi
• Granted Patent: US 8,868,228 B2
• Time in Patent Office: Days
• US Class Current: 700/189
• CPC Class Codes: G05B 19/41 characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 19/416 characterised by control of velocity, acceleration or deceleration G05B19/19 takes precedence

Abstract

When a numerical controller executes a tool-center-point control in which a path of a tool center point with respect to a workpiece is instructed, and the workpiece is machined along the instructed path based on a speed instruction, the numerical controller sets the speed instruction so that the speed instruction is a synthesis speed with respect to a synthesis distance of a relative moving distance between the workpiece and a tool center point and a tool-direction changing distance due to a relative change in a tool direction with respect to the workpiece by a rotary axis. The numerical controller interpolates a position of a linear axis and a position of a rotary axis by the tool-center-point control according to the synthesis speed and drives the linear axis and the rotary axis to the position of the linear axis and the position of the rotary axis created by the interpolation.

Claims

1. A numerical controller for controlling a multi-axis machining device which machines a workpiece mounted on a table by using at least three linear axes and at least one rotary axis while changing a relative direction of a tool with respect to the workpiece,

wherein said numerical controller, for executing a tool-center-point control in which a path of a tool center point with respect to the workpiece is instructed so as to move and machine the workpiece along the instructed path of the tool center point based on a speed instruction, comprises:

a synthesis speed control unit that sets said speed instruction so that said speed instruction is a synthesis speed with respect to a synthesis distance of a relative moving distance between the workpiece and a tool center point and a tool-direction changing distance due to a relative change in a tool direction with respect to the workpiece by the rotary axis; and

an interpolation unit that interpolates positions of the linear axes and a position of the rotary axis by the tool-center-point control based on the speed instruction according to the synthesis speed,

wherein the linear axes and the rotary axis are driven to the positions of the linear axes and the position of the rotary axis created by the interpolation unit.

2. The numerical controller according to claim 1, wherein said at least one rotary axis is two rotary axes for rotating the table, and the tool-direction changing distance is obtained from an equation below:

Drt=Σ

√

{square root over (ka*Δ

ra² kb*Δ

rb² (ra*Δ

4)² (rb*Δ

B)²)}{square root over (ka*Δ

ra² kb*Δ

rb² (ra*Δ

4)² (rb*Δ

B)²)}

in which

Drt;

Tool-direction changing distance

ra;

Distance from a rotation center of an A axis (as one rotary axis) to the tool center point

rb;

Distance from a rotation center of a B axis (as another rotary axis) to the tool center point

Δ

ra;

Amount of change in ra for each simulation cycle

Δ

rb;

Amount of change in rb for each simulation cycle

ka;

Weighting coefficient of Δ

ra

kb;

Weighting coefficient of Δ

rb

Δ

A, Δ

B;

Amount of change of A axis and B axis for each simulation cycle.

3. The numerical controller according to claim 1, wherein said at least one rotary axis is two rotary axes for rotating the table, and the tool-direction changing distance is obtained from an equation below:

4. The numerical controller according to claim 1, wherein the rotary axis is a rotary axis for rotating a tool head, and the tool-direction changing distance is obtained from an equation below:

Drh=Σ

√

{square root over (kc*Δ

rc (ra*Δ

A)² (rc*Δ

C)²)}{square root over (kc*Δ

rc (ra*Δ

A)² (rc*Δ

C)²)}

in which

Drh;

Tool-direction changing distance

ra;

Distance from a rotation center of an A axis (as one rotary axis) to the tool center point

rc;

Distance from a rotation center of a C axis (as another rotary axis) to the tool center point

Δ

rc;

Amount of change in rc for each simulation cycle

kc;

Weighting coefficient of Δ

rc

Δ

A, Δ

C;

Amount of change of A axis and C axis for each simulation cycle.

5. The numerical controller according to claim 1, wherein said at least one rotary axis is two rotary axes for rotating a tool head, and the tool-direction changing distance is obtained from an equation below:

Drh=√

{square root over (kc*(rce−

rcs) ra²*(Ae−

As)² rcn²*(Ce−

Cs)²)}{square root over (kc*(rce−

rcs) ra²*(Ae−

As)² rcn²*(Ce−

Cs)²)}{square root over (kc*(rce−

rcs) ra²*(Ae−

As)² rcn²*(Ce−

Cs)²)}

in which

Drh;

Tool-direction changing distance

As, Cs;

Position of A axis (as one rotary axis) and position of C axis (as another rotary axis) at the start point of the path of the tool center point

Ae, Ce;

Position of A axis and position of C axis at the end point of the path of the tool center point

ra;

Distance from the rotation center of the A axis to the tool center point

rcs;

Distance from the rotation center of the C axis to the tool center point at a position Cs of the C axis at the start point of the path of the tool center point

rce;

Distance from the rotation center of the C axis to the tool center point at a position Ce of the C axis at the end point of the path of the tool center point

rcn;

Value representative of the distance from the rotation center of the C axis to the tool center point in a block

kc;

Weighting coefficient of (rce−

rcs).

6. The numerical controller according to claim 1, wherein said at least one rotary axis is two rotary axes for rotating the table and a tool head, and the tool-direction changing distance is obtained from an equation

Drm=√

{square root over (Drt² Drh²)}

or from an equation

Drm=Drt Drh

in which

Drt is a tool-direction changing distance calculated by a C axis (table-rotating axis) with respect to the rotation of the table and expressed by the following equation

Drt=Σ

√

{square root over (ka*Δ

ra² kb*Δ

rb² (ra*Δ

A)² (rb*Δ

B)²)}{square root over (ka*Δ

ra² kb*Δ

rb² (ra*Δ

A)² (rb*Δ

B)²)}

in which

Drt;

Tool-direction changing distance

ra;

Distance from a rotation center of an A axis (as one rotary axis) to the tool center point

rb;

Distance from a rotation center of a B axis (as another rotary axis) to the tool center point

Δ

ra;

Amount of change in ra for each simulation cycle

Δ

rb;

Amount of change in rb for each simulation cycle

ka;

Weighting coefficient of Δ

ra

kb;

Weighting coefficient of Δ

rb

Δ

A, Δ

B;

Amount of change of A axis and B axis for each simulation cycle, or expressed by the following equation

7. The numerical controller according to claim 2, wherein the ra and rb are set values, program instruction values, or constant values.

8. The numerical controller according to claim 3, wherein ras, rae, ran, rbs, rbe, and rbn are set values, program instruction values, or constant values.

9. The numerical controller according to claim 4, wherein the ra and rc are set values, program instruction values, or constant values.

10. The numerical controller according to claim 5, wherein the ra, rcs, rce, and rcn are set values, program instruction values, or constant values.