Thread measurement tool

A thread measurement tool comprising:

• a sensor assembly;
• means for affixing said sensor assembly contiguous to the thread of a pipe section;
• a set of probe means for sensing the locations of troughs of the thread, at least one of the probe means of the set being slideably mounted within said assembly in two directions one of which is normal to the longitudinal axis of the pipe section and the second of which is parallel to the axis of the pipe section, each of said probe means including a probe and means coupled to said probe for measuring a displacement of the probe in each of the two directions for obtaining the coordinate of a trough in normal and axial components;
• each of said probes having a ball-type contact for setting within a trough of the thread, said displacement measuring means including a first transducer for the sensing of longitudinal motion of the probe and a second transducer for the sensing of translational motion of the probe, the longitudinal motion corresponding to movement in a direction normal to said pipe axis and said transverse motion corresponding to motion along the axis of the pipe;
• and wherein
• said assembly includes a pair of legs extending therefrom and spaced apart from each other for contacting said thread at spaced locations and supporting said assembly on said thread, said affixing means including an arm pivotably connecting with an end portion of said assembly distant from said probes and extending from said assembly for contacting a second surface of the wall of the pipe section opposite said thread at a location corresponding to a site between said pair of legs to inhibit motion of said assembly relative to the thread in an axial plane of the pipe section, said arm terminating in a pair of contact elements on opposite sides of a plane joining said pair of legs to inhibit motion of said assembly relative to said thread in a direction normal to said plane;
• and
• means coupled to said transducers for combining measurements of probe displacements in a direction normal to said longitudinal axis of the pipe section to provide for the determination of deviation in diameter of said pipe section.

A portable, automatic thread inspection tool for measuring a plurality of parameters on a pipe thread and the like in situ irrespective of whether the thread is internal or external to the pipe, comprising:

• (a) frame means adapted to be readily installed over the wall of a pipe from the pipe end,
• (b) means located on the frame means for generating a first signal representative of the thread height error,
• (c) means located on the frame means for generating a second signal representative of the thread lead error,
• (d) means located on the frame means for generating a third signal relating to average taper of the thread,
• (e) means associated with the frame means for receiving the first, second and third signals and generating a display of the thread height error, thread lead error and average thread taper relating to the thread being measured.

A probe assembly for use in a thread measurement tool to measure thread height error automatically when the tool is installed on the thread, the thread having a crest portion and a trough portion and the assembly having a transducer with a case and core wherein the relative positions of the case and core generate a signal indicative of the measurement comprising:

• (a) means on the tool for mounting the transducer case for movement towards and away from the thread;
• (b) probe collar means attached to the case having a portion thereof which seats itself on the crest portion of the thread;
• and
• (c) probe tip means attached to the transducer core for movement relative to the collar means which seats itself into the trough portion of the thread;
• whereby the relative positions of the probe tip and probe collar determine the relative positions of the transducer core and transducer case for automatically generating a signal representative of the thread height.

A method of automatically measuring one or more parameters of a pipe thread and the like in situ which an electronically operating tool comprising:

• (a) installing a thread measuring tool having two pivotally joined arms over the end of a threaded pipe so that a first arm of the tool engages the external surface of the pipe and a second arm of the tool engages the internal surface of the pipe, one of said arms carrying a sensor assembly with a set of spaced, aligned probes that produce respective electrical measurement signals for the measurement of desired parameters of the pipe thread,
• (b) placing the probes into operative contact with the thread at respective spaced locations thereon that lie in a common axial plane through the pipe,
• (c) determining the position of the sensor assembly relative to the end of the pipe,
• (d) activating the sensor assembly trough control means,
• (e) measuring height error on the thread with electrical signals obtained from at least one probe in the set of probes, and
• (f) measuring lead error of the thread with electrical signals obtained from at least one other probe in the set of probes,
• (g) repeating steps (b) through (f) at a circumferentially displaced location on the pipe thread,
• whereby rapid measurements of multiple parameters of the thread can be made accurately because it is unnecessary for the operator to directly interact with the probes during the measuring process.

A method of automatically measuring taper of a pipe thread and the like in situ with a tool comprising:

• (a) installing the tool on the pipe thread, the tool having a sensor assembly including an inclinometer means,
• (b) activating the inclinometer means through a control means for providing a first measurement relating to the average taper of the thread relative to a given reference plane,
• (c) storing the first measurement,
• (d) reinstalling the tool at an angularly displaced position on the thread from the installation location of step (a),
• (e) reactivating the inclinometer means through the control means for providing a second measurement relating to the average taper of the thread relative to the given reference plane, and
• (f) subtracting the second measurement from the first measurement to determine the average taper of the thread whereby the average taper of the thread can be determined accurately and rapidly without dependence on the operator's direct interaction with the sensor assembly due to the hands off nature of the tool once installed and activated.

A method of automatically measuring height error, lead error, cumulative lead, average taper, interval taper and pitch line deviation of a pipe thread and the like in situ with the same tool comprising:

• (a) installing a tool having a sensor assembly thereon with a set of probes and an inclinometer means,
• (b) activating the sensor assembly through a control means,
• (c) measuring height error of the thread with at least one probe in the set of probes,
• (d) measuring lead error of the thread with at least one other probe in the set of probes,
• (e) measuring and storing a first value relating to average taper of the thread relative to a given reference plane,
• (f) measuring pitch line deviation of the thread at a given number of intervals over the thread,
• (g) reinstalling the tool at an angularly displaced position on the thread from the installation location of step a,
• (h) reactivating the inclinometer means through the control means for measuring a second value relating to average taper of the thread to the given reference plane,
• (i) subtracting the second value from the first value to determine the average taper of the thread, and
• (j) reactivating the sensor assembly through the control means to measure pitch line deviation of the thread at the given number of intervals while the tool is reinstalled on the thread,
• whereby at least one reading is obtained for height error, lead error, cumulative lead, average taper and interval taper and the non-linearity of the pitch line can be determined.