Coordinate measuring machine pdf


 

Position. • Actual size is obtained by probing the surface at discrete measuring points. Every pt is expressed in terms of its x,y,z coordinates. Functions of CMM. CMM. 3D coordinate measuring machines from Mitutoyo: The new dimension of quality assurance. Today's manufacturing demands more accuracy, speed. CMM. 3D coordinate measuring machines from Mitutoyo: the new dimension of quality assurance. Today's manufacturing demands more accuracy, speed.

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Coordinate Measuring Machine Pdf

PDF | 25+ minutes read | Coordinate measuring machines in various branches of industry within last years became very common. Measuring machines can be. PDF | Traditional touch trigger probes are widely used on most commercial coordinate measuring machines (CMMs). However, the CMMs with these probes . PDF | In this research work, a comparative study between the precision obtained with a touch probe (TP) and that obtained with a scanning.

Machine body[ edit ] The first CMM was developed by the Ferranti Company of Scotland in the s [1] as the result of a direct need to measure precision components in their military products, although this machine only had 2 axes. Leitz Germany subsequently produced a fixed machine structure with moving table. This moves freely along the granite table with one leg often referred to as the inside leg following a guide rail attached to one side of the granite table. The opposite leg often outside leg simply rests on the granite table following the vertical surface contour. Air bearings are the chosen method for ensuring friction free travel. In these, compressed air is forced through a series of very small holes in a flat bearing surface to provide a smooth but controlled air cushion on which the CMM can move in a frictionless manner. The movement of the bridge or gantry along the granite table forms one axis of the XY plane.

Coordinate Measuring Machine Measurement Planning

Measurement accuracy and precision improved dramatically with the invention of the electronic touch trigger probe. The pioneer of this new probe device was David McMurtry who subsequently formed what is now Renishaw plc. As the probe touched the surface of the component the stylus deflected and simultaneously sent the X.

Y,Z coordinate information to the computer. Measurement errors caused by individual operators became fewer and the stage was set for the introduction of CNC operations and the coming of age of CMMs. Optical probes are lens-CCD-systems, which are moved like the mechanical ones, and are aimed at the point of interest, instead of touching the material.

The captured image of the surface will be enclosed in the borders of a measuring window, until the residue is adequate to contrast between black and white zones.

The dividing curve can be calculated to a point, which is the wanted measuring point in space.

The horizontal information on the CCD is 2D XY and the vertical position is the position of the complete probing system on the stand Z-drive or other device component. There are newer models that have probes that drag along the surface of the part taking points at specified intervals, known as scanning probes. This method of CMM inspection is often more accurate than the conventional touch-probe method and most times faster as well.

The next generation of scanning, known as noncontact scanning, which includes high speed laser single point triangulation, [3] laser line scanning, [4] and white light scanning, [5] is advancing very quickly. This method uses either laser beams or white light that are projected against the surface of the part. Many thousands of points can then be taken and used not only to check size and position, but to create a 3D image of the part as well.

This "point-cloud data" can then be transferred to CAD software to create a working 3D model of the part. These optical scanners are often used on soft or delicate parts or to facilitate reverse engineering.

Probing systems for microscale metrology applications are another emerging area. Technologies to achieve microscale probing include scaled down version of classical CMM probes, optical probes, and a standing wave probe [8] among others.

However, current optical technologies cannot be scaled small enough to measure deep, narrow feature, and optical resolution is limited by the wavelength of light.

X-ray imaging provides a picture of the feature but no traceable metrology information. Fringe projection systems, theodolite triangulation systems or laser distant and triangulation systems are not called measuring machines, but the measuring result is the same: Laser probes are used to detect the distance between the surface and the reference point on the end of the kinematic chain i. This can use an interferometrical function, focus variation , light deflection or a beam shadowing principle.

Portable CMMs with articulated arms have six or seven axes that are equipped with rotary encoders, instead of linear axes. Portable arms are lightweight typically less than 20 pounds and can be carried and used nearly anywhere. However, optical CMMs are increasingly being used in the industry.

Designed with compact linear or matrix array cameras like the Microsoft Kinect , optical CMMs are smaller than portable CMMs with arms, feature no wires, and enable users to easily take 3D measurements of all types of objects located almost anywhere.

Certain nonrepetitive applications such as reverse engineering , rapid prototyping , and large-scale inspection of parts of all sizes are ideally suited for portable CMMs.

The benefits of portable CMMs are multifold. They are easy to use and do not require a controlled environment to take accurate measurements. The inherent trade-offs of portable CMMs are manual operation they always require a human to use them. In addition, their overall accuracy can be somewhat less accurate than that of a bridge type CMM and is less suitable for some applications.

Traditional CMM technology using touch probes is today often combined with other measurement technology. This includes laser, video or white light sensors to provide what is known as multisensor measurement.

To verify the performance of a coordinate measurement machine, the ISO series is available. This series of standards define the characteristics of the probing system and the length measurement error:. From Wikipedia, the free encyclopedia. This article needs additional citations for verification.

Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: Retrieved CIRP Annals, , Measurement Science and Technology. Bauza; R.

Coordinate-measuring machine

J Hocken; S. T Smith; S. C Woody Sci Instrum, 76 9 Measurements taken by this contact method were often unreliable as machines were moved by hand and each machine operator applied different amounts of pressure on the probe or adopted differing techniques for the measurement.

Operators no longer had to physically touch the machine but could drive each axis using a handbox with joysticks in much the same way as with modern remote controlled cars. Measurement accuracy and precision improved dramatically with the invention of the electronic touch trigger probe.

The pioneer of this new probe device was David McMurtry who subsequently formed what is now Renishaw plc. As the probe touched the surface of the component the stylus deflected and simultaneously sent the X. Y,Z coordinate information to the computer.

Precision tracking control of a horizontal arm coordinate measuring machine

Measurement errors caused by individual operators became fewer and the stage was set for the introduction of CNC operations and the coming of age of CMMs. Motorised automated probe head with electronic touch trigger probe Optical probes are lens-CCD-systems, which are moved like the mechanical ones, and are aimed at the point of interest, instead of touching the material. The captured image of the surface will be enclosed in the borders of a measuring window, until the residue is adequate to contrast between black and white zones.

The dividing curve can be calculated to a point, which is the wanted measuring point in space. The horizontal information on the CCD is 2D XY and the vertical position is the position of the complete probing system on the stand Z-drive or other device component.

New probing systems[ edit ] There are newer models that have probes that drag along the surface of the part taking points at specified intervals, known as scanning probes. This method of CMM inspection is often more accurate than the conventional touch-probe method and most times faster as well. The next generation of scanning, known as noncontact scanning, which includes high speed laser single point triangulation, [3] laser line scanning, [4] and white light scanning, [5] is advancing very quickly.

This method uses either laser beams or white light that are projected against the surface of the part. Many thousands of points can then be taken and used not only to check size and position, but to create a 3D image of the part as well.

This "point-cloud data" can then be transferred to CAD software to create a working 3D model of the part. These optical scanners are often used on soft or delicate parts or to facilitate reverse engineering. Micrometrology probes Probing systems for microscale metrology applications are another emerging area.

However, current optical technologies cannot be scaled small enough to measure deep, narrow feature, and optical resolution is limited by the wavelength of light. X-ray imaging provides a picture of the feature but no traceable metrology information.

Fringe projection systems, theodolite triangulation systems or laser distant and triangulation systems are not called measuring machines, but the measuring result is the same: a space point. Laser probes are used to detect the distance between the surface and the reference point on the end of the kinematic chain i.

This can use an interferometrical function, focus variation , light deflection or a beam shadowing principle. Portable CMMs with articulated arms have six or seven axes that are equipped with rotary encoders, instead of linear axes.

Coordinate Measuring Machine Measurement Planning | SpringerLink

Portable arms are lightweight typically less than 20 pounds and can be carried and used nearly anywhere. However, optical CMMs are increasingly being used in the industry. Designed with compact linear or matrix array cameras like the Microsoft Kinect , optical CMMs are smaller than portable CMMs with arms, feature no wires, and enable users to easily take 3D measurements of all types of objects located almost anywhere.

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