moving from process inspection to process control: cmms take the lead.
Over the past 40 years, coordinate measuring instruments have increasingly been used as reliable equipment to collect dimensional data used in measurement and inspection applications. CMMs is a flexible offering of highaccuracy, high- Throughput Measurement is more cost-effective than the expensive custom gauge used in many manufacturing operations. Quality control and manufacturing engineers found that, Number of process detection Qualified parts shipped to customers, the power of dimensional data analysis is to apply the results to the control of the processing operation. To meet this demand, CMM manufacturers focus their development efforts on improving speed, accuracy and real-time performance Time data collection and analysis capabilities for process control application CMMs. In the workshop, improved process control reduces the possibility of productionof- Tolerance parts to reduce scrap and rework. The closer the application of the result is to real-time, the greater the value of the result in the control process. Moving CMMs from the inspection room to the workshop is a step towards a real goal Time process control. The use of CMM for workshop measurement helps to reduce production costs, improve inspection throughput, and establish a database of the behavior history of machines, parts, pallets and fixtures during actual processing. However, the challenge is to protect CMMs from environmental temperatures, vibrations and air contaminants found in the workshop environment. In the past few years, meeting this challenge has always been one of the driving forces for the development of CMM technology. The CMMs designed for workshop service are made of materials that resist temperature changes and vibrations. A cmm recently launched from Brown & Sharpe was built around the use of steel bearings. All other components of the machine have thermal properties similar to steel to minimize the impact of temperature changes on measurement accuracy. The X- Shaft rack and Z Shaft ram is made of aluminum/sic matrix material with similar expansion coefficient as steel. A high- The density polymer composite substrate has similar thermal properties, plus it hardens the machine, providing ten times more vibration damping than conventional materials. The base also absorbs high Frequency noise is found in the workshop, further reducing the time impact of vibration on measurement accuracy. To improve reliability, all key drivers are completely closed. The circulating bearing assembly is sealed to resist contaminants in the air, so the life is high and the maintenance cost is low. Another challenge in measuring the inspection of large parts workshops is the measurement and inspection of large workpieces. Due to their size, there are special handling and fixing problems with these workpieces. What makes these parts difficult to measure is not only their dimensions, but also the various characteristic tolerances that are often found on them. Since larger parts require more time to check, the focus is on using a portable coordinate meter to check large workpieces. There are many ways to detect large parts, including laser tracker and photographic measurement system. Optical measurement system and optical CMMs. Each of these methods has the benefit of measuring the large parts they are located in the workshop without having to transfer the parts to the inspection area. Each technology also provides a relatively high Speed measurement when compared to other in-situ methods. What each is missing is the high precision required by the dimensions to define the features, such as the exact hole diameter and position as part of a larger structure. One way to solve the problem of accuracy and throughput in the inspection operation is The contact sensor technology using the traditional touch trigger probe technology on the coordinate measuring instrument. Increase of non- The contact sensor of the coordinate measuring instrument combines high With all the typical features of the CMM, such as easy programming, quick reconfigure, high accuracy, and getting results off- Line CMMs equipped with traditional probes. This practice meets the requirements of the production cycle time. Contact sensor measurement element based on single image acquisition obtained by single positioning, plus high Speed characteristic of CMMs used for inspection of large workpieces in production environment. Two non-regions Contact sensor technology for measuring large workpieces are laser stripe scanners and optical sensors that use CCD cameras and suitable lighting equipment. Both types of sensors are integrated with light sources and photoelectric detectors and work based on the principle of triangulation. The light source emits a laser or infrared beam of precise focus. When this beam hits the surface of the workpiece, it forms an image of a point. The diffuse scattered light is then focused on the photoelectric array. Any change in the distance from the time surface of the time sensor will result in a change in the position of the spot image on the array. The laser sensor works by projecting a light strip on the surface of the part that makes a virtual copy of an existing part or shape. This virtual 3D copy consists of a series of measured points, each with its own XYZ coordinates in space. This point cloud is used to perform inspection or reverse engineering. The laser sensor is a highly accurate data acquisition device, but it covers less areas than the CCD Optical sensors. The working principle of the CCD optical sensor is to associate the pixels of the image or image taken by the sensor with the corresponding 3D points in the frame part area. It actually allows to reconstruct all the time points within its field of view at the same time. The wide range of data acquisition areas of CCD optical sensors allows the execution of detection programs very quickly. For example, the cycle time was significantly shortened compared to the tactile probe measuring the same features, 1. For non-5 seconds Contact the sensor compared to 16 seconds of the time tactile probe. Collect data points by touching the surface of the part, continuously scanning the touch trigger probe. These probes are very accurate, but they collect data faster than they areContact sensor. Continuous scanning is a touch probe technique that keeps the probe in contact with the surface of the workpiece. Continuous scanning is a way to automatically collect large amounts of data points that can accurately define the shape of the part. Scanning provides more data points for analysis in the same period of time, or more data points in a shorter period of time Point contact trigger probe technology. The high- Fast data collection speeds make it possible to determine the size, position and shape at the same time with high repeatability and accuracy. Combination of non- Contact and contact data collection sensors in a single CMM can solve many problems related to checking large parts, and can also create a large dimension database for historical reference. Probe positioning for accurate, multiple Sensor measurement. In the process of data collection, part accessibility restrictions often require frequent orientation of the head, which sometimes results in a reduction in effective overall system throughput unless the sensor is installed in the hinged bracket. Continuous two-axis and three- The shaft servo wrist is the solution to this problem. These wrists are designed to quickly locate any posture of the probe in accordance with the precise 3D trajectory. Their speed and motion are continuously controlled by the system controller to achieve maximum machine efficiency. If necessary, the servo wrist is guaranteed to be completely accessible through the extension cord, and the precision loss is minimal. The sensor goes through three- The CMM regards it as any other standard probe, so all sensor functions are integrated and managed by the software. Working software in parallel with workshop CMMs and data acquisition sensor development is the development of advanced measurement and detection software. CMM is controlled by a distributed processing architecture that includes controllers and master computers. The software manages all machine functions, operator interfaces, part programming, and 3D data analysis. The software provides an interface between the sensor and the computer for efficient data exchange. Advanced Measurement and inspection software provides a direct interface with CAD systems for more accurate part programming. Advanced Measurement and inspection software is seamlessly linked to CAD systems and provides interactive graphics for the generation of mathematical models and the verification of carved surfaces. Direct CAD interface (DCI) , Available with PC- DMIS measurement and inspection software, no software is required to translate the original CAD model in any way, ensuring that the parts are programmed using accurate design data. The user can create the part program directly on the CAD model, which reduces the programming time and improves the accuracy. DCI also simplifies and accelerates reverse engineering applications by facilitating interaction between CMM and CAD/CAM systems. Software is also easier to use for workshop operators. PC- For example, the dmis one touch software allows the operator to just TOUCH the features of the part being checked. The software automatically recognizes the feature type and creates an interactive graphical representation of the part on the screen. For other measurement requirements, on- Board training module helps operators with practical hands before, during and after programming and part executionon advice. Measurement help and lessons learned are driven by realistic, online parts drawingsthe-job training. Measurement software is also developing to equipment other than CMMs. PC- DMIS recently launched pcdmis nc for machine tools. PC- Combined with PCDMIS measurement and inspection software, dmis nc can monitor the manufacturing process in real time, providing CAD comparisons for measuring points and CAD surfaces for quick and accurate analysis of results. Where will CMM technology go in the future? The development of controller protocol is an important area. Joint control of the inspection activities of the agreement to increase efficiency and value, allowing for a variety Proprietary software packages for metering applications. Open architecture software enables users to increase the value of measurement systems by integrating them more easily into the manufacturing process. An alliance of users, manufacturers, universities and government agencies is currently working to create a common driver for measurement (MCD) , A set of common standards that will be located between the user\'s software and the hardware controller, allowing the hardware to be controlled by any software that supports the MCD. This approach to integrated metering operations will provide users with significant improvements in productivity, throughput, and efficiency. Brown and sharp, www. rsleads. com/312tp-