3D scanning is a high-tech integrating optical, mechanical, electrical and computer technologies. It is mainly used to scan the spatial shape and structure of an object to obtain the spatial coordinates of the object surface. Its significance lies in that it can convert the three-dimensional information of the object into a digital signal that can be directly processed by the computer, which provides a very convenient and efficient means for the digitization of the object.
Three-dimensional scanning technology can realize non-contact measurement, and has the advantages of high speed and high precision. And its measurement results can be directly interfaced with a variety of software, which makes it very popular today with the increasing popularity of CAD, CAM, CIMS and other technical applications. In the manufacturing industry of developed countries, as a fast three-dimensional measurement equipment, 3D scanners are more and more used due to its advantages of fast measurement speed, high precision, non-contact, and convenient use. Use the 3D scanner to scan the hand plate, sample and model to obtain its three-dimensional size data. These data can be directly interfaced with CAD/CAM software. In the CAD system, the data can be adjusted, repaired, and sent to the machining center or rapid prototyping. Manufacturing on equipment can greatly shorten the product manufacturing cycle.
The three-dimensional scanning equipment is mainly based on the three-dimensional measurement system. Basically, there are two types of contact type (probe type) and non-contact type (laser, photography, X-ray equation). In the early days, the probe type was mainly used. Although the price was cheaper, the speed was slow, and the connection between the probe and the object would have blind spots and easily deform the software object, which would affect the scanning accuracy. It can have high measurement accuracy and is suitable for relative size measurement and quality management; the laser scanning speed is fast and the accuracy is appropriate, and it can scan three-dimensional objects to obtain a large amount of point cloud data to facilitate surface reconstruction, which can be read out on the computer after scanning Data, this part is called reverse engineering preprocessing.
Development of reverse engineering technology and equipment
Today, with the high development of computers, the three-dimensional geometric modeling technology has been widely used in the design of molds, program evaluation, automatic processing and manufacturing, management and maintenance in the manufacturing industry. However, there is often such a problem, that is, the customer only has a physical sample or a hand-wrench model, and there is no CAD data file of the drawing, so the engineers cannot get the accurate size, and it is even more difficult to manufacture the mold. The traditional engraving method takes a long time and the effect is not good. At this time, it is necessary to use various measurement methods and three-dimensional geometric modeling methods to convert the original object into a three-dimensional digital model on the computer. This is called reverse engineering (Reverse Engineering).
Reverse engineering includes rapid reverse, rapid prototyping, rapid mold and multi-degree-of-freedom CNC machining. Among them, the development of fast inversion is the gradual development from traditional contact measurement to fast non-contact measurement, especially with the development of "optical mechatronics" technology, which combines computer, image processing, laser technology and precision machinery The 3D laser scanner has gradually become the mainstream of reverse engineering. The three-dimensional laser scanning has developed from point scanning measurement to line scanning measurement and field measurement in form. Line scanning measurement and point scanning are also based on the "triangulation measurement principle", and at the same time, with the help of high-precision, high-resolution surface Array CCD image acquisition system, so that it has high measurement accuracy similar to the point scanning form and high efficiency comparable to the field measurement method. In addition, the stepper motor is used to drive the rotating platform, and the full contour data information of the measured object can be obtained, and the three-dimensional shape information of the object can be obtained by 3D scanning.