US 4,555,955 A · Combination loading transducer

Abstract

The performance and condition of a tool, workpiece or machine tool is sensed during machining operations by securing a single or plural strain gages to the tool holder. To increase the sensitivity of the strain gages on stationary tool holders, the tool holders are contoured to provide locations of higher strain in which the strain gages are attached. A single or plural strain gages are positioned to sense the combined effect of different strains such as axial thrust and torque and are electrically connected to provide a single Wheatstone bridge output "signature" which may be monitored to detect a defective operation. In rotating tools, the single "signature" output greatly reduces the coupling equipment such as rotary transformers and also reduces the monitoring equipment. A unique arrangement of a single strain gage or alternatively a plurality of gages enables monitoring of both torque and thrust simultaneously. The output from the plurality of strain gages can be made additive to increase sensitivity and yet requires only a single bridge circuit. The design is flexible in that the gages may be arranged for optimization of the single bridge output for either torque or thrust.

Claims24

Dependent claims

A torque and thrust sensor for machine tools of the type in which the machine provides a source of drive power to a tool, the tool being applied to the workpiece in order to perform work thereon, comprising:

(a) a tool holder connected between the source of drive power and the tool to supply the drive power to the tool, the tool holder comprising:
(i) a central axis running generally from the source of drive power to the tool,
(ii) a first flange having its principal surface oriented generally orthogonal to the central axis of the tool holder,
(iii) a second flange having its principal surface oriented generally orthogonal to the central axis of the tool holder and its principal surface positioned apart from and facing the principal surface of the first flange,
(iv) a plurality of beams connected at one of their ends to the principal surface of the first flange and at their other ends to the principal surface of the second flange, the connection to the flanges being adjacent the periphery of the flanges and the beams each being connected at an angle phi with respect to the central axis for bending in response to torque or axial loading of the tool holder.
(b) a strain gage device mounted on a beam and oriented to measure a desired strain in the beam produced by the operation of the tool on the workpiece.

3 more elements

A transducer for sensing the effects of axial and torsional loading and providing an electrical output indicative thereof comprising:

(a) body means including first end means defining a first surface adapted for receiving input torsional and thrust loading about an axis, said body means further including second end means defining a reaction surface adapted for transmitting said input loading to a reaction member and elastically strainable structure disposed intermediate said first surface and said reaction surface, said strainable structure including gaging structure defining a sensing surface, said gaging structure defining the region of maximum stress in said strainable structure;
(b) a single strain gage disposed on said sensing surface, said strain gage having the sensing direction thereof oriented at an acute angle in the range 15.degree.-30.degree. with respect to the axis of loading for sensing effects of combined torsion and thrust loading and,
(c) bridge circuit means operative, upon connection to a source of electrical power, to apply an electrical potential to said strain gage and operative to detect changes in the resistance of said gage in response to said combined torsion and thrust loading of said transducer and operative to provide an output signal indicative of said loading.

Dependencies are inferred from the claim text.

Combination loading transducer

Life of this patent

Combination loading transducer

Life of this patent

Abstract

Claims24