Thread Gauge Research Articles

Experimental investigation of novel internal thread fabrication: A drill thread milling

In this study, a novel method for fabricating internal threads called drill thread milling (DTM) was experimentally investigated. DTM is a fabrication process that combines drilling and thread milling into a single process, thereby eliminating the need for a pilot hole and making it a viable alternative to existing methods. To optimize the DTM process, the characteristics of DTM must first be understood. In this study, the machining characteristics of DTM were examined using a variety of materials and machining parameters. The results were then compared with those obtained using the tapping method. During the experiments, the machining force and vibration were recorded, and the results indicated that DTM required less machining time than did the tapping method. However, DTM exhibited an additional periodic components in the machining force, which could resulted in chatter. In certain materials, a tool offset was required to pass the thread gauge, indicating substantial tool deflection occurred during the machining process. The examination of the resulting threads revealed that, for the same thread depth, DTM required a shallower hole than that required in the tapping method.

Verification of a calibration method for 3D screw thread metrology

The novel approach for holistic screw thread calibrations developed by the Physikalisch-Technische Bundesanstalt was published in 2019. A significant achievement has been made in order to meet increasing demands in manufacturing processes and quality assurance, particularly when workpieces with complex geometries are under inspection. This article deals with the verification of the previously presented three-dimensional calibration procedure for screw threads. Screw thread pitch diameters, the lead and flank angles are compared to those determined by the standardized method based on line-like, rather two-dimensional measurements and evaluation. In order to provide a reliable basis for the verification, one thread gauge was calibrated under laboratory conditions for precision metrology. Additionally, calibrations were conducted by three alternating operators on three different coordinate measuring machines to investigate the influence by user and machine. The resulting normalized errors of screw thread determinants under test and reference values are significantly smaller than 0.5 which indicates a high level of agreement.

Compensation of thread profile distortion in image measuring screw thread

The thread measuring method possesses an efficient and easy to install with image measurement of axial section but results in thread profile distortion. Through the geometric analysis of the axial section projection image of the screw thread, it is confirmed that phenomenon of thread profile distortion always exist in measuring screw thread by projection image, meanwhile, the requirements of depth of focus is put forward with the method, calculation formula of thread profile distortion is deduced, and the corresponding compensation algorithm is given; through the simulation, analysis of coarse thread, it found the distortion has influence in thread angle and pitch diameter significantly, reaching 2.3% and 3.36% respectively, the unilateral shaded proportion of the thread profile in the root region is up to 7.12%, but the root diameter itself remains unaffected mostly. Take metric coarse thread gauge as measurement object, and compared the results with tool microscope, experiments show that the compensation effect is more than 85% in pitch diameter, more than 70% in thread angle.

Multi Objective Optimization of machining parameters for Hard Turning OHNS/AISI H13 material, Using Genetic Algorithm

Oil Hardened Non-Shrinking Die Steel (OHNS/AISI H13) are employed in the production of callipers, plug gauges, thread gauge, punches and milling cutters for its hardness and good machinability performance. This experimental works focused on maximizing metal removal rate (MRR) and minimizing surface roughness (Ra) by choosing the optimal turning parameters. L27 Orthogonal array based experiments were conducted in CNC Supertech 6.2 turning centre using carbide insert CNMG 120408. The individual and interaction effects of cutting speed (v), feed rate (f) and depth of cut (ap) on MRR and Ra is analyzed in Design Expert 9.0 Software. Empirical models are framed which reveals the relationship between the turning parameters and output responses. Non-Traditional optimization technique genetic algorithm is used with multi objective function to find the optimum parameters in turning AISI H13 steel materials. Confirmation experiments are performed to validate the optimum results of genetic algorithm and it is within the acceptance limit.

Investigation on the Grinding Ability of Thread Gauge Material under Different Heat Treatment

Investigation on the Grinding Ability of Thread Gauge Material under Different Heat Treatment

Investigation on temperature distribution in form grinding of 9Mn2V thread gauge

Accurate simulation about the grinding temperature distribution helps to decrease the thermal damage and microcracks during the grinding process. In this article, the grinding heat transfer process of form grinding was analyzed and a temperature distribution model was derived in form grinding of 9Mn2V thread gauge. Considering the characteristics of form grinding, the temperature rise of the intersection region can be affected by two kinds of heat sources, and the impact between the two heat sources has been investigated. Also, the influence of the grinding depth on the temperature rise was analyzed. Depending on the analysis, an improved heat partition model has been derived, which is based on single-grain energy partition model. A series of experiments were carried out to investigate the grinding performance of 9Mn2V. The grinding force was obtained, the specific grinding energy was discussed, and the experimental temperature was measured by infrared imager. It is shown that the experiment results correspond well to the theoretical temperature calculated by the prediction model. This temperature model can be used to optimize the grinding conditions and the critical depth in form grinding of 9Mn2V thread gauge.

Investigation on the Metrology of Conical Thread Gauge

This paper presents a new method for the calibration of conical thread gauges. The procedure involves scanning of conical thread profiles, extracting all the thread main parameters, reconstructing the conical thread model. The metrologies model compared to the Standard one that is established on the basis of theoretical data. Thereby, the actual state of the threads can be fully identified by means of Screwing into the threaded length, which is good for control of the thread quality

Experimental investigation on the effects of different heat treatment processes on grinding machinability and surface integrity of 9Mn2V

This paper investigated the grinding machinability and surface integrity of premium thread gauge material 9Mn2V in conventional surface grinding by using seeded gel (SG) abrasive (3SG80KV) under different heat treatment processes. Serious meshy segregation of carbide, excessive amounts of retained austenite, coarse and inhomogeneous distribution of material structure were significant causes of grinding burn and grinding crack. In order to improve the abrasion resistance and mechanical properties of workpiece material, cryogenic and tempering treatment was added. After adopting cryogenic and tempering treatment for two times, the disappearance of the meshy segregated carbide and network carbide was eliminated, the amount of the retained austenite content was within 4 %, and martensite became much more fine and homogeneous. The grinding experiment results indicated that workpiece material 9Mn2V could provide superior grinding integrity with the occurrence of grinding burn and grinding cracks reduced by using this process.

Analysis of the Pitch Diameter Measurement Based on Three-Pin/T-Shaped Probe and Thread Scanner

To study the data consistency of Three-pin/T-shaped probe and thread scanning measurement. Through the analysis and summary of the measurement methods and experimental data obtained in two methods of measurement uncertainty can meet the thread gauge diameter measurement requirements. Experiment to obtain the maximum difference of the actual size of the corresponding point of 1.1μm, verify the correctness of the two thread measurement method and propose the appropriate application program.

Study on Grinding Crack of Premium Thread Gauge Material 9Mn2V

This paper investigates the surface integrity of premium thread gauge material 9Mn2V in reciprocating surface grinding using SG abrasive, which includes metallographic structure for grinding crack, specific grinding energy and surface residual stress. The specific grinding energy and the surface residual stress can be reduced after the workpiece gets tempered, so small grinding depth can lead to the generation of cracks when the workpiece is not tempered. Otherwise, the depth of heat affected zone increases with the increase of grinding depth, but not increases proportionally. After 9Mn2V is tempered, the occurrence of grinding burn and grinding cracks can be improved.

Measurement of a cross-sectional profile of a thread gauge using a sinusoidally vibrating interference pattern

A sinusoidally vibrating interference pattern (SVIP) is used as an exact spatial scale in order to measure a cross-sectional profile of a thread gauge. The SVIP is projected on the thread gauge surface, and lights diffracted and reflected from the end points of the thread gauge surface are extracted by spatial frequency filtering in an imaging system to make an image of the end points whose positions are decided by the peak positions of amplitude distributions in the image. The coordinates of the end points or the cross-sectional profile of the thread gauge is obtained from the phases measured at the positions of the end points, phase distribution of the SVIP on a CCD image sensor, and the pixel positions of the CCD image sensor.

Alignment problem while measuring thread pitch of large thread gauges on the profile-measuring machines

The problem described in this paper arises while measuring pitch of the large-scale thread gauges with a profile-measuring machine. Analytic estimate of the thread gauge alignment uncertainty is given, which results in the accumulated error of the thread pitch measurement. The results proposed in this paper should be considered as an additional source of uncertainty while inspecting the thread pitch on profile-measuring machines.

Determining alignment in measurement of a large-diameter thread by means of devices for profile measurement

An analytic estimation of the inaccuracy of the alignment of a thread gauge on a device that must be taken into account in the measurement of the accumulated error of the thread pitch is given. For an M170.6 thread, the measurement error of the accumulated pitch reaches 0.008 mm on a length of 200 mm.

Determining alignment in measurement of a large-diameter thread by means of devices for profile measurement

An analytic estimation of the inaccuracy of the alignment of a thread gauge on a device that must be taken into account in the measurement of the accumulated error of the thread pitch is given. For an M170.6 thread, the measurement error of the accumulated pitch reaches 0.008 mm on a length of 200 mm.

A New Method for Thread Calibration on Coordinate Measuring Machines

This paper presents a new method for the calibration of thread gauges on coordinate measuring machines. The procedure involves scanning of thread profiles using a needle-like probe, achieving traceability by substitution of different thread portions with corresponding paths on a calibrated sphere. The feasibility of applying the method to calibrate a parallel thread gauge with respect to all the relevant thread parameters was demonstrated experimentally using a precision CMM. Application of the comparator approach as described in ISO DTS 15530-3 gave measuring uncertainties comparable to the values from usual calibration methods on dedicated equipment, e.g. a measuring uncertainty of 1.8 μm was achieved for measurement of the pitch, and 2-2.5 μm for diameter measurements.

Development and application of computer aided design software for thread gauge

Development and application of computer aided design software for thread gauge

THE SETTING OF SCREW THREAD ROLL GAUGES WITHOUT MASTER THREAD PLUGS

According to standard handbooks and inspection practice, screw thread roll gauges are set by employing special master set plugs. In the present paper, formulae are developed to enable thread wires and gauge blocks to serve the same purpose. The appropriate exact formulae, as well as approximate, easily applicable ones, are derived for symmetrical triangular and trapezoidal threads and the non-symmetric case deduced from the previous results.

Investigation of new universal measuring microscopes

1. The measurement errors of microscopes of the new system are at the same level as those of the UIM-21 and the Zeiss microscopes, with the exception of the error in measuring Dav of a thread gauge by means of the shadow method and the error in measuring the profile angle of a thread. 2. The larger error in measuring Dav and the profile angle as compared with similar existing instruments is due to the imperfections of certain units in the design. 3. The errors in measuring the diameters of smooth cylindrical gauges by the shadow projection and axial cross-section methods are considerably smaller than those obtained from the formulas of the manufacturing plant. 4. The manufacturing plant should indicate in the instrument's operating instructions the error in measuring a plane angle and provide a formula for the errors in measuring profile angles of thread gauges. 5. The utilization of wax screens in the sighting and display devices has not reduced the precision of the instruments, but at the same time has made them more convenient in work and tends to reduce the fatigue of the tester, thus raising the productivity of his labor. 6. The screens can be used for sighting not only in the shadow projection method, but also in the axial cross-section method. 7. Testing of the UIM-23 and UIM-24 instruments has shown that only in measuring the mean diameter of threads by the shadow projection method do the instrumental, technological, and adjustment deficiencies of these instruments have a most pronounced effect on the precision of their readings and the measurement error. Therefore, in drafting standards or procedure instructions for testing these instruments it is necessary to specify requirements for measuring the Dav of thread gauges by means of the shadow method.