Development Of A Grating Two-dimensional Scanning Probe

The CMM is a high precision, high efficiency three-dimensional measuringinstrument for measuring the dimensions of three-dimensional to meet the highertesting requirements of machining production line, CNC machine and automaticprocessing production line, which is a important tool of modern industrial production.The probe is an important part of the coordinate measuring machine as a keycomponent of precision measurement. In recent years, with the rapid development ofcoordinate measuring technology, a variety of precision measuring head emerged.Probe is developed commonly use inductive components as sensor, which is moreexpensive.For the status of the current probes, developed a new type of gratingsensor-based two-dimensional scanning probe, the main contents are as follows:Studied the development and course of probe, and the development status of theprecision probe is reported. With the current advantages and disadvantages ofcommonly used probes in the course of an investigation, to clarify research projectssignificance and the expected goals, two-dimensional scanning probe design as thecore of overlap parallel reeds and the grating sensor.A mechanical model of the parallel spring structure is established, and thevarious errors and the deformation of the probe performance are quantitativeanalysised. Under this premise, to determine the mechanical main part of thetwo-dimensional scanning probe combinations and size, and the check of stress. Theparallel spring rail with high precision and sensitivity, the two coordinate directions ofoverlapping, making the spatial structure is more compact. Grating displacementsensor as the displacement components of feelings, a detailed comparied of thecharacteristics and usage of the existing grating displacement sensor to determine theselection and installation of two-dimensional scanning probe grating. Also, lockingmechanism and over-travel protection are designed.The grating signal processing part has been made, including the amplifier shapingmodule, FPGA module and DSP module, work on the grating signal processing andcounting up the machine data transfering the counted data to computer. Threeinterfaces are designed, the ISA interface, RS232and the USB interface circuit.Prepared a host computer software to complete the acquisition of the output signal ofthe probe.This paper uses the experimental method to verify the feasibility of probe. Theexperimental results show that in the range of measurement as500μm theresolution of probe is0.125μm, the maximum repeatability error is1μm, and themaximum linearity error is1.27μm. The probe working stable with goodrepeatability,which has achieved the design requirements.