255results about "Error compensation/elimination" patented technology

A thermal deformation error compensation method for a coordinate measuring machine creates thermal deformation and geometric error data at different ambient temperatures including temperatures and machine kinematic parameters to obtain a thermal deformation and geometric error model, and inputs the model into central control unit of the coordinate measuring machine, and converts a 3D error compensation to obtain a thermal deformation and geometric error compensation model, and uses the thermal deformation and geometric error compensation model for performing compensations, so as to complete a thermal deformation and geometric error compensation of the coordinate measuring machine.

A method of compensating the measurement errors of a measuring machine that derive from the deformations of the machine bed caused by the load exerted by the workpiece to be measured on the machine bed, comprising a first acquisition step in which data regarding the weight of the workpiece and the modes of resting of the workpiece on the machine bed are acquired, and a second calculation step in which correction values depending upon said data are calculated.

A series of nominally identical production workpieces is measured on a measuring apparatus. To correct for temperature variations, one of the workpieces forms a master artefact, the dimensions of which are known. The artefact is measured on the measuring apparatus at two or more temperatures, producing two or more corresponding sets of measured dimensional values of the master artefact at the respective temperatures. One or more error maps, look-up tables, or functions are generated which relate the measured dimensional values of the artefact to the known dimensions of the artefact. The error map(s), look-up table(s) or function(s) are dependent on the respective temperatures at which the artefact was measured. Correction values derived from the error map(s), look-up table(s) or function(s) are used to correct the measurements of production workpieces in the series. These correction values are determined in dependence upon the temperature at which the workpiece measurements were obtained.

A machine, such as a coordinate measuring machine, having an element and a structure movable with respect to each other along rails, wherein the rails have a different coefficient of thermal expansion than the structure to which they are attached. In one embodiment, a bar is disposed on the structure opposite the rails. This bar has a coefficient of thermal expansion, a stiffness, a spacing from the neutral axis of the structure, and a cross-sectional dimension such that the bar balances any thermal stresses in the structure caused by differential expansion or contraction of the structure and the rails with temperature changes to minimize any bending of the structure. In one embodiment, two rails are disposed on a beam, and a carriage travels on the two rails. For each rail, there is an associated bar disposed on an opposite surface of the beam. In another aspect, a pin extends into an elongated slot on a slide associated with the structure to allow the structure to expand and contact. In yet another aspect, a movable element, such as a carriage, is coupled to an associated slide riding along the rails by a leaf spring to accommodate expansion and contraction of the element.

A surface processor uses an environmental profile to determine the sub-surface length of tubing disposed in a well bore. Information relating to tubing properties is stored in a memory module of the surface processor. The environmental profile includes data relating to well bore ambient conditions and the operating parameters of well equipment. Surface processor calculates the tubing elongation or length reduction corresponding to the environmental profile. Surface processor may repeat this process to develop a measured depth chart for a well. Logging operations performed in conjunction with the sub-surface length calculations allows formation data to be associated with the measured depth chart.

A probe head for a coordinate measuring machine has a feeler device that can be deflected in space. Also provided are balancing element for adjusting a predetermined rest position of the feeler device for any different alignment of the probe head in space. The balancing element are designed as masses. The forces or moments required for balancing the feeler device are produced by the masses.

The invention discloses a projection lens system. The projection lens system sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power and a diaphragm from an object side to an image side along an optical axis, and is characterized in that an object-side surface of the first lens is a convex surface; an image-side surface of the third lens is a convex surface; and the optical centers of the lenses are located at the same straight line. The projection lens system satisfies the following conditions: f12>f3, (dn/dt)1<-50*10<-6>/DEG C, (dn/dt)2<-50*10<-6>/DEG C, and (dn/dt)3>-10*10<-6>/DEG C, wherein f12 represents the combined focal length of the first lens and the second lens, f3 represents the focal length of the third lens, and (dn/dt)1, (dn/dt)2 and (dn/dt)3 respectively represent changes rates of refractive indexes of the first lens, the second lens and the third lens along with the temperature. The projection lens system can cancel out influences imposed on the focal length by thermal expansion brought about by the lenses and structural members due to reasonable distribution of the change rate of the refractive index of each lens along with the temperature, thereby being capable of realizing stable focal length and being applicable to different temperature occasions.

In a machine tool having an on-board measuring machine and controlled by a numerical controller, a method of measuring a shape of a workpiece presets a reference point for temperature drift correction on the workpiece, moves a probe to the reference point, resets a coordinate system of the probe to correct a temperature drift of the probe, and carries out shape measurement of the workpiece along a first measuring path. Next, the method moves the probe to the reference point again, resets the coordinate system of the probe to correct a temperature drift of the probe again, and carries out shape measurement of the workpiece along a second measuring path. Thereafter, similar temperature drift correction is carried out for each measuring path until the shape measurement of the workpiece is carried out along the last measuring path.

Methods are described for measuring series of nominally identical production workpieces on a dimensional measuring apparatus such as a coordinate measuring machine. One master workpiece of the series is calibrated, to provide correction values which are used to build an error map of the measuring apparatus. This map is used to correct measurements not only of subsequent nominally identical workpieces of the same series, but also of multiple different subsequent series of different workpieces. Each subsequent series also has a master workpiece which is calibrated and used to further build the error map. As this process is repeated over time, the error map becomes more and more densely populated. In due course, it becomes possible to dispense with the use of a calibrated master workpiece, because measurements can be corrected using error values which already exist in the error map.

A method for determining an “effective” thermal coefficient of a machine comprises the steps of installing one or more temperature sensors (110) at various locations on the machine, positioning a first machine member (60) at a “known” reference location, relative to a second machine member (42), installing a linear position measuring device (120) to detect changes in position of the first machine member (60) relative to the second machine member (42) along a first axis of movement, periodically acquiring readings from each of the temperature sensors (110) and from the linear position measuring device (120) during a test cycle and compiling the temperature and linear position data into a table. A statistical correlation analysis is performed to determine which of the temperature sensors (110) experiencing changes in temperature are most linearly related to changes in the linear position of the first machine member (60) relative to the second machine member (42) and an “effective” coefficient of thermal expansion is thereafter determined as the rate of change of position, i.e. length, relative to change in temperature. The present method includes using the machine's “effective” thermal coefficient the calibrate the motion of the machine to compensate for the thermal characteristics thereof.

A method for calibrating a triangulation sensor including a light emitting unit for emitting measuring light and a light receiving unit. The light emitting unit is arranged with known position and orientation relative to the light receiving unit and the triangulation sensor which is adapted to provide triangulation-based position measurements. A calibration setup which comprises the triangulation sensor and a calibration target providing a defined calibration pattern, and a calibration measurement is performed with reference to the calibration target by means of the triangulation sensor. An image of the calibration target is captured by means of the light receiving unit, and the captured image is processed with deriving a pattern image position with reference to the inner sensor image coordinate system and deriving a light image position with reference to the inner sensor image coordinate system.