Adaptive thrust sensor drilling

An apparatus for performing a drilling operation on a stackup of materials for an aircraft, the apparatus comprising:

• a housing;
• a spindle capable of receiving a drill bit, wherein the spindle has a base;
• a spindle motor capable of turning the spindle at a set of different speeds during a drilling operation, wherein a drilling speed comprises at least one of a speed at which the spindle turns and a speed at which a thrust motor moves the spindle in an axial direction;
• the thrust motor capable of moving the spindle in the axial direction, wherein the thrust motor has a positive drilling speed when the thrust motor moves the spindle axially away from the base, a neutral drilling speed when the thrust motor does not move the spindle, and a negative drilling speed when the thrust motor moves the spindle axially towards the base;
• a load sensor capable of detecting a reaction thrust force during the drilling operation to form a detected reaction thrust force, wherein the load sensor is located around the base;
• a controller capable of controlling the spindle motor and the thrust motor to change the drilling speed in response to changes in the detected reaction thrust force;
• and
• program code executable by the controller to change the drilling speed during the drilling operation, wherein the program code comprises a process, layer definitions, and material definitions in which the layer definitions defines a set of layers in a stackup for the drilling operation, a change in a reactive thrust force value indicating when a new layer is reached in the set of layers, and a thickness of a layer used to identify a distance for performing the drilling operation when a change in the detected reaction thrust force is not used to control the drilling speed and in which the material definitions defines the drilling speed for a material in the material definitions and a normalized hardness used to identify a layer transition within the set of layers;
• and wherein the layer definitions include a peck wait thrust value that specifies a distance the drill bit must travel after completing a full peck motion and moving forward in a material before reading another reactive thrust force value from the load sensor.

A method for performing a drilling operation on a stackup, the method comprising:

• monitoring, by a load sensor, a reactive thrust force value during the drilling operation;
• responsive to a change in the reactive thrust force indicating a new layer, identifying the new layer, wherein the new layer becomes a current layer in the drilling operation;
• and
• specifying a distance a drill bit must travel after completing a full peck motion and moving forward in the current layer before reading another reactive thrust force value from the load sensor.

A method for performing a drilling operation on a stackup of materials for an aircraft, the method comprising:

• identifying a current layer in a plurality of layers in the stackup using layer definitions;
• selecting a drilling speed for the materials in the current layer from material definitions for the plurality of layers to form a selected drilling speed;
• causing a spindle to move at the selected drilling speed using the selected drilling speed, wherein the drilling speed for the drilling operation based on a material in the current layer being drilled includes a speed at which the spindle turns and controlling a speed at which the spindle moves axially;
• monitoring a reactive thrust force during the drilling operation;
• responsive to a change in the reactive thrust force indicating a new layer, identifying the new layer, wherein the new layer becomes the current layer in the drilling operation;
• specifying a distance a drill bit must travel after completing a full peck motion and moving forward in the current layer before reading another reactive thrust force value from a load sensor;
• ending the drilling operation when all of the plurality of layers has been drilled;
• controlling the drilling speed of the drilling operation based on a distance that a drill bit has traveled into the stackup if changes in the reactive thrust force are not used to control the drilling speed;
• and
• controlling a speed at which the spindle moves axially to perform a peck operation.