Force and torque sensor for machine tools

A sensor for use with a machine tool in which substantially all of the load on a first machine tool member is borne by a second machine tool member, said sensor being responsive to displacement of the first machine tool member to measure the force and torque exerted thereon and comprising:

• first means mounted in proximity to the first machine tool member, said first means including:
• a plurality of pressure chambers, each of which is filled with an incompressible fluid, said pressure chambers being disposed in pairs that are orthogonally disposed about the longitudinal axis of the first machine tool member;
• a plurality of membranes corresponding in number to said pairs of pressure chambers, each of said membranes being composed of a rigid material and each forming at least one wall of each of the pressure chambers within one of said pairs thereof;
• and, means measuring the pressure within each of said pressure chambers;
• a plurality of elongated pressure arms corresponding in number to said membranes and each being composed of a rigid material;
• and,
• second means affixing a first end of each of said pressure arms to the first machine tool member at a location along said longitudinal axis thereof at which force and torque are to be measured so that a second end of each of said pressure arms bears on a corresponding one of said membranes in said first means.

A sensor responsive to displacement of a machine tool member for measuring the transverse force exerted thereon, said machine tool member being rotatable with, affixed to, and primarily supported by the spindle of a machine tool, said sensor comprising:

• a receptacle module affixed to and rotatable with the spindle, said receptable module including a first pressure chamber that is filled with an incompressible fluid and that has a membrane extending transversely to a first sensor axis which is transverse to the axis of rotation of the machine tool member, a second pressure chamber that is filled with an incompressible fluid and that has a membrane extending transversely to a second sensor axis that is angularly disposed about said axis of rotation relative to said first sensor axis, and means measuring the pressure within each of said first and second pressure chambers;
• first and second pressure arms, a first end of each of said pressure arms being affixed to the machine tool member at a location along said axis of rotation at which transverse force is to be measured, said first and second pressure arms extending in parallel to said axis of rotation toward said receptable module and second ends thereof respectively bearing normally on the membranes of said first and second pressure chambers, whereby the pressures within said first and second pressure chambers are related to the components of transverse force along said first and second sensor axes, respectively.