Measurement Accuracy Investigation of Touch Trigger Probe with Five-Axis Machine Tools (original) (raw)

Influence of measured objects parameters on CMM touch trigger probe accuracy of probing

Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology - PRECIS ENG, 2005

Influence of the measured objects parameters on coordinate measuring machine (CMM) touch trigger probe inaccuracy of probing is investigated. Factors such as material stiffness of measured workpiece, its surface shape and roughness are taken into consideration. The measuring method out off CMM, based on a rotary table and a reference axis is applied for tests. The concept is based on measurements of the distance between reference and triggering points in various directions. The reference points are established by the rotation of a precise rotary table. The statistical analysis of variance and regression is applied for data analysis.

Factors Influencing Probing Accuracy of a Coordinate Measuring Machine

IEEE Transactions on Instrumentation and Measurement, 2005

The analysis of probe operational parameters such as configuration of the probe, including triggering (measuring) force, stiffness, and length of the stylus, has been performed. A new method allowing three-dimensional (3-D) probe error characteristics with several times more accuracy than the procedure used on a coordinate measuring machine (CMM) has been applied. The analyses have been performed for devices of two types: a single-stage and a two-stage switching probe. The influence of the above-mentioned parameters has been analyzed theoretically and verified experimentally in two planes: perpendicular and parallel to the probe axis. Good agreement between the proposed theoretical model and experimental data has been obtained. Index Terms-Coordinate measuring machine (CMM), dimensional metrology, one-stage and two-stage probes, probing accuracy.

Setup for Triggering Force Testing of Touch Probes for CNC Machine Tools and CMMs

Measurement Science Review, 2013

Touch-trigger probes are commonly used both in coordinate measuring machines (CMM) and in computer numerical control (CNC) machine tools. In both cases accuracy of measurement of the overall system and probing unit are closely interrelated. Key parameters of the probes are repeatability and pre-travel variation dependent on adjustable stylus force. To enable testing of the triggering force of the probes, the new setup was developed. The principle of the method and setup is presented and its validity is experimentally confirmed.

CMM touch trigger probes testing using a reference axis

Precision Engineering, 2005

A new method of testing of touch trigger probes for coordinate measuring machines (CMM) has been proposed. The concept is based on measurements of the distance between reference and triggering points in various directions. The reference points are established by the rotation axis of a precise rotary table. The advantage of this method relies on easy realisation with application of a commercial device for roundness error measurement. The accuracy of the presented method is much higher in comparison with the existing procedures of CMM probes calibration. The mathematical principle of the method has been presented and used for evaluation of its uncertainty. The validity of the method was experimentally confirmed by means of one-and two-stage type probes.

Development of a low cost Touch Trigger Probe for CNC Lathes

Journal of Materials Processing Technology, 2006

The use of Touch Trigger Probes for CNC Machine Tools has become a world standard, mainly due to the reduction of machine setup time and the ability to promote workpiece accuracy on-machine measurements. However, some barriers still need to be transposed, like the measurement routines programming difficulties, high costs of these equipments and the low number of technical literature about this subject. This work presents a review on the applications of Touch Trigger Probes on shop floor, discussing nowadays technologies used to generate the trigger signal. A new Touch Trigger Probe model based on a simple electrical contact is proposed, with the needed characteristics and low cost, to be used for CNC Lathes. The tests of the probe developed in the laboratory shown a repeatability of 0.003 mm (±3 s or 99.73% confidence interval). Those characteristics seem to be highly comparable to most needs for lathe applications in industries.

Evaluation of Touch Trigger Probe Measurement Uncertainty Using FEA

2006 IEEE Instrumentation and Measurement Technology Conference Proceedings, 2006

Evaluation of measurement uncertainty is an essential subject in dimensional measurement. It has also become a dominant issue in Coordinate Measuring Machine (CMM) even though its machine performance has been well accepted by many users. CMM probes, especially touch trigger probes which are commonly used, have been acknowledged as a key error source, largely due to pretravel variations. The probe errors result in large measurement uncertainty in CMM measurement. Various methods have been introduced to estimate measurement uncertainty, but they tend to be time consuming and necessarily require a large amount of experimental data for analyzing the uncertainty. This paper presents the method of evaluation of CMM probe uncertainty using FEA modeling. It is started with the investigation of the behavior of probe by recording stylus displacement with vary triggering force. Then, those displacement results will be analyzed with sensitivity analysis technique to estimate the uncertainty of recorded results.

Traceability of On-Machine Tool Measurement: A Review

Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close measurements and fast feedback into their manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They provide the possibility to measure the workpiece in-machine during or after its manufacture, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable enough for process control or product validation. The scientific objective is to determine the uncertainty on a machine tool measurement and, therefore, convert it into a machine integrated traceable measuring process. For that purpose, an error budget should consider error sources such as the machine tools, components under measurement and the interactions between both of them. This paper reviews all those uncertainty sources, being mainly focused on those related to the machine tool, either on the process of geometric error assessment of the machine or on the technology employed to probe the measurand.

Error compensation for CMM touch trigger probes

Precision Engineering, 1996

We present the analysis of a simple mechanical model of a common type of kinematic seat touch trigger probe widely used on modern coordinate measuring machines (CMMs). The model provides a quantitative description of the pretravel variation or "probe-lobing'" characteristics that fimit the use of such probes for high-accuracy dimensional measurements. We include the effects of stylus bending and the frictional interaction between the stylus ball and the part surface. The model is restricted to probes with simple straight styli, and we demonstrate significant error reduction both for vertically and horizontally oriented stylL In the latter case, gravitational forces are shown to play an important role in probe triggering and pretravel variation. Extensions to arbitrary orientations are discussed.

Practical aspects of touch-trigger probe error compensation

Precision Engineering, 1997

We present extensions to our prior work in modeling and correcting for pretravel variation errors in kinematic seat touch-trigger coordinate measuring machine (CMM) probes with straight styli. A simple correction term is shown to account for a range of probe asymmetries quantitatively, leading to improved error compensation. We also demonstrate probe lobing correction for constrained fits to small datasets, illustrating practical examples for both CMM and machine tool probes. Finally, we discuss statistical and uncertainty issues and demonstrate the effectiveness of the model with actual measurement data.