Thread Angle Research Articles

Dimensional Error Analysis of Cortical Screw during Threading of Magnesium AZ31

Developments in manufacturing to achieve large productivity and high-quality products in the modern era have necessitated the need of using suitable methods. Taguchi or robust design method has been implemented to optimise a process in a single response. This experiment aims to analyse the cutting parameters of geometrical errors of threads. Machining trials were conducted on the diameter of the workpiece (10, 14 and 18 mm), depth of cut (0.23, 0.3067 and 0.46 mm) and spindle speed (212, 318 and 424 rpm). Three responses, namely, pitch, height threads and angle thread error, were investigated. The external thread selected is metric M1,5 with three levels of three factors. Results show that spindle speed was the most significant factor that affected pitch error and height thread error. Depth of cut and diameter of the workpiece significantly affected thread angle error. The optimal condition to produce low thread angle error included machining at level 1 diameter of the tool, level 3 depth of cut of and level 3 spindle speed.

Improved design of self-tapping screw (STS) for Korean larch and red pine cross laminated timber (CLT)

In this study, the finite element method (FEM) was used to determine the effect of the optimal angle of the thread and double thread application among self-tapping screw (STS) design information on the improvement of the withdrawal capacity of the connection. It was modeled by reflecting the design information of an Italian STS distributed in the domestic wooden building market, and the stress distribution of the connections was compared according to the change in the thread angle. A cross laminated timber (CLT) composed of five layers was modeled as a member. The STS modeling was centered on the threaded area, and two threaded angles were applied: 90° and 95°. Additionally, the stress changes were compared when double threads located in the middle of the thread pitch in the screw pitch were applied to improve the withdrawal capacity of the connection. The domestic STSs were manufactured using four materials and two shapes. The finite element analysis and strength performance tests of the STS types indicated that the material properties, angle of the screw thread, and shape of the screw thread affect the Korean CLT withdrawal capacity.

Tensile behavior of parallel threaded couplers for reinforcements by natural cooling after elevated temperatures

Parallel threaded couplers (PTC) are increasingly being applied to prefabricated concrete (PC) structures owing to their excellent structural performance. To evaluate the effect of high temperatures on the tensile behavior of PTC, the specimens were cooled to natural temperature after the fire (400 ℃, 500 ℃, and 700 ℃), and monotonic and cyclic tests were carried out on PTC with two thread angles (60° and 75°). After the test, the failure mode, ultimate bearing capacity, load-displacement curve, and ductility of PTC were investigated. The results show that the failure mode of PTC is steel bar necking, and the ultimate load of PTC after the fire are reduced by 6.7 %, 7.3 %, and 11.1 % under the monotonic test, the connection performance of mechanical splices is excellent. Besides, the finite element model was established to simulate the mechanical properties of PTC. The load-displacement curves and the constraint effect of the sleeve obtained by the finite element simulation corresponded well with the tests. Based on this agreement, a parametric study was carried out to investigate the effect of the thread pitch and thread angle on the ultimate bearing capacity and ductility of PTC, and the constraint effect of the sleeve on the thread head was further investigated by the finite element parametric analysis.

Study on the rate of change of thread angle and thread distance considering the interference factor under before and after the dynamic vibration of the fastening system

Precision nuts are widely used in tool spindles and ball screws. Proper locking gives the bearing the right amount of pre-pressure so that the inner balls can roll steadily and inhibit friction and rapid temperature rise. If no pre-pressure is given to the bearing, it will cause the inner ball to slide irregularly and generate extremely high temperatures. In this paper, the precision nuts used are the flank locking precision locked nut and clasp locking precision locked nut for Taguchi method experiments. The control factors are nut type, Fitting clearance, and lubrication oil. Interference factors are surroundings temperature, assembly personnel, and torque wrench. The purpose is to obtain more suitable anti-loosening characteristics by the Taguchi method under the influence of interference factors and to check the thread angle and thread pitch before and after the experiment. The experimental results were analyzed form Taguchi method to find the combination of parameters with the maximum S/N and the variance analysis to obtain the significant factor. Finally, the regression equation of the loosening prevention characteristics was obtained by regression analysis, which shows that the optimized parameters effectively improve the loosening prevention characteristics and explore the interference factor on the loosening prevention characteristics of precision nuts.

Improving dental implant stability by optimizing thread design: Simultaneous application of finite element method and data mining approach

Lack of knowledge regarding the optimal design of thread configuration in dental implants, which can offer a satisfactory level of stability in the implant-bone construct, is a significant challenge in the field of dental biomechanics. The purpose of this finite element analysis study was to identify the optimal thread design by investigating the effects of thread parameters such as thread depth (TD), thread width (TW), and thread pitch (TP), as well as upper (α) and lower (β) thread angles, on the maximum principal stress in cancellous and cortical bone, maximum von Mises stress in the dental implant, and maximum shear stress at the implant-bone interface. A finite element model of an alveolar bone segment with a dental implant was developed. The Latin hypercube sampling method was used to generate a dataset of virtual experiments, which were analyzed by using the decision tree method to identify suitable thread designs that minimize mechanical stimuli. Additionally, the effectiveness of thread parameters on stress levels in the bone, implant, and their interface were assessed. The results of this study, verified by comparison with previous literature, indicated that TD, TW, and upper thread angle were the most effective parameters in promoting implant stability. By analyzing the decision trees, optimum ranges for all the thread parameters were determined as follows: 0.25<TD<0.34, 0.25≤TW≤0.28, 0.8≤TP≤0.88, 66.2≤α≤80, and β≤65.4, which led to the V-shape thread design.

Rancang Bangun Pembangkit Listrik Pikohidro Menggunakan Turbin Screw Pada Aliran Danau PCR

Picohydro is a power plant that produces 5 kW of power which consists of 3 components, namely air flow, turbine, and generator to convert maximum energy into electrical energy. Picohydro is an alternative power plant as a substitute for fossil fuel power plants (diesel and gasoline). The PCRlake flow has a flow of 0.019 m3/s which can be used as a potential source of energy to generate electricity, where the tools used are screw turbines, V-belt transmission, and DC generators. The results of the design of the screw turbine that are made have a turbine length specification of 1,140.5 mm, an outside diameter of 419.4 mm, an inside diameter of 225 mm, a turbine pitch of 503.2 mm, a number of blade turns 2 pieces, a turbine angle of 26o, a thread angle of 21o, and a head of 0.5 m. For the transmission, there are 2 type A -V belts that connect the turbine rotation to the DC generator rotation. The results obtained that the theoretical power available in the PCR lake flow is 95.01 watts. The average rotation produced by the 1,398 rpm generator is able to stably turn on as many as 6 DC lamps with a total load of 60 watts. By testing the DC lamp load, a total load of 60 watts produces a generator power of 29.14 watts, a screw turbine power of 34.08 watts. By testing using a braking system at turbine rotation it produces a maximum torque of 13.12 Nm with a screw turbine power of 46.70 watts and a turbine mechanical efficiency of 49.16%.

Novel dual thread angle sampled multioscillatory-based control for speed ripple reduction in a switched reluctance machine-based drive

The paper presents a novel control method based on a dual thread speed controller with modified multi-oscillatory control for speed ripple reduction in a switched reluctance machine-based drive. The method is based on on-line phase current shaping. The paper describes a dual thread angle-sampled multi-oscillatory control (ASMOSC) theory for speed ripple reduction of a switched reluctance machine under variable speed. Description of the entire cascaded speed control system with linear controllers is also provided, along with an implementation description for ASMOSC. This includes practical hints on how to apply the control system to a dual core microcontroller. The frequency-domain stability analysis for a designed control system under variable speed conditions is presented. The overall performance of the control system is verified numerically and experimentally on a laboratory setup with an 4-phase 8/6 SRM-based drive.

Accuracy of Thread Profile Depends on the Lathe Tool Angle of Inclination. Theoretical Investigation

Among threaded connections of large sizes, tapered thread pipe connections are especially often used, which are a very important part of drill strings. The efficiency of the drill strings largely depends on the accuracy of the tool-joint tapered thread. The production of such joints is implemented on lathes, with the help of tools that have a carbid insert. To ensure high performance, such inserts are recommended to be installed not parallel to the axis of the thread, but at the lead angle of thread. However, the profile of the insert itself is equal to the profile of the thread, and therefore it is important to have a theoretical predictive calculation of the probable influence of the angular setting of the carbide insert on the accuracy of the thread. Based on a detailed consideration of the geometry of the mutual placement of the plate and the tapered thread and the kinematic features of the process, an algorithm for predictive calculation of the accuracy of the thread is created. The result shows that only one of the parameters of the cutting edge really depends on the angle of inclination of the cutting edge - it is its profile. The deviation can reach 7% of the tolerance on the semi-profile angle.

Effect of thread angle besides other process parameters in electromagnetically crimped threaded surfaced tube-to-tube joint: FEM modelling and ANOVA analysis

The electrical, power, and automotive industries use copper-steel (Cu-SS), a peculiar material combination, in various applications. The current work deals with electromagnetically crimped threaded surfaced Cu-SS tube-to-tube (EMCT3) joints, as the deformation behavior of the joints cannot be predicted or examined using the FEM methods previously presented. Therefore, the present work develops a non-coupled multi-step FEM model for analyzing the deformation during EMCT3 joining, the strength of the produced joint, and its experimental verification. A good agreement between experimental and simulation results is observed with an error range of 5–12%. Furthermore, ANOVA analysis shows that the contribution % of thread angle, thread pitch, and discharge energy is 32.99%, 41.35%, and 19.22 %, respectively, towards strength.

Optimization of thread configuration in dental implants through regulating the mechanical stimuli in neighboring bone

Background and objectiveThe threads, as the most critical component of dental implants, transfer the imposed occlusal loads to the adjacent bone. Moreover, regulation of the mechanical stimuli in the implant adjacent bone is crucial to maximize the bone-implant construct stability. An optimal thread design can be resulted when the distribution of mechanical stimuli within the bone, and at the implant-bone interface, lie in an advised confined range. In this work, with the goal of finding the optimal thread design, which can provide the maximum level of stability, the effects of thread parameters, namely, thread depth, thread width, and thread pitch, together with upper and lower thread angles, on maximum principal strain within the cortical and cancellous bone, and shear strain at the implant-bone interface, were investigated. MethodsIn this study, the response surface methodology (RSM), due to the central composite design (CCD), was employed to obtain a set of 53 experiments. Following that, they were numerically simulated using the finite element method (FEM). The polynomial regression model was then used to predict the response functions based on the magnitude of thread parameters. The effectiveness of each thread parameter was also evaluated through statistical tools. Moreover, the non-dominated sorting genetic algorithm (NSGA-II) was performed to find the optimum dimensions of the thread. ResultsThrough comparing the results obtained from analyzing initial and optimized configuration of threads, it was shown that the latter causes a reduction in the maximum principal strains in cancellous and cortical bones by about 25% and 30%, respectively, which is in favor of making a higher quality bone, and thus greater stability in dental implant-bone construct. Moreover, the maximum shear strains at the implant-bone interface in different planes were reduced by about 40%, in the optimized thread, compared with the initial design. ConclusionsThe optimized design found in this study is a buttress thread with a fine pitch, but deep thread, which keeps the mechanical stimuli in a safe range to grant an acceptable level of stability.

An Optimized Dental Implant Model Using Finite Element Analysis and Design of Experiment

Purpose: To develop, analyze, and optimize a dental implant by considering square threads and varying the thread dimensions to obtain an optimal shape. Materials and Methods: For this study, finite element analysis (FEA) and numerical optimization method were integrated to develop a mathematical model. The critical parameters of dental implants were studied, and an optimized shape was obtained using response surface method (RSM) and design of experiment (DOE). The simulated results were then compared to the predicted values under optimal conditions. Results: Using the one-factor RSM design model for the dental implant and a vertical compressive load of 450 N for testing, the optimal depth to width ratio for the thread was 0.7 in order to achieve the minimum von Mises and shear stress. Conclusion: The buttress thread was found to be the optimal shape for achieving the lowest von Mises and shear stress compared to square threads, and the thread parameters were calculated accordingly, with a thread depth 0.45 times the pitch, a width 0.3 times the pitch, and a thread angle of 17 degrees. Also, due to the constant diameter of the implant, common 4-mm diameter abutments can be used interchangeably.

Automatic Measurement of External Thread at the End of Sucker Rod Based on Machine Vision.

Aiming at the low efficiency of manual measurement of threads and the lack of practicability in machine vision measurement before, online size measurement of threads at the end of sucker rods based on machine vision was studied. A robotic arm is used to carry an optical device to achieve high-quality image acquisition of threads. Based on the prior knowledge of the thread profile angle, the directional edge detection operator is customized to achieve the accurate detection of the left and right edges of the thread. Noise filtering, sorting, and left and right edge-matching algorithms based on connected domains are developed to eliminate the interference effects of electrostatic dust and oil pollution in online measurement, and the dimension of thread profile angles, pitches, major diameters, and minor diameters can be precisely calculated. The experimental results show that the screw thread parameter measurement time is about 0.13 s; the maximum and minimum average errors of the thread angles are 0.011° and 0.632°, respectively; and the total average deviation is less than 0.08°. For the screw thread pitch, major diameter, minor diameter, and pitch diameter parameter measurement, the deviation of the measurement results between the proposed method and the universal tool microscope (UTM) method is less than 10 μm. It fully proves the effectiveness and accuracy of the method in this paper and, at the same time, shows that the method has good real-time performance and high application significance, which lays a good foundation for the subsequent online thread measurement.

Impact of technological and operational deviations of the thread flank angle on the fatigue life of the tool joint

The total effect of technological and operational factors can lead to various types of deviations of the flank angle of the tool joint thread profile, which are uneven along the axis. It is shown that uneven deviations of the flank angle appear when tapered threading with a lathe tool with a non-zero rake angle. To analyse the effect of these deviations on the fatigue strength of the joint, a parametric axisymmetric finite element model of the ZN-80 tool joint was developed in Abaqus/CAE. In the fe-safe program, dependences of the fatigue life in the thread roots on the deviations of the flank angle of the pin thread were obtained. The box thread has not been changed. To increase the fatigue strength of the pin, in most of the cases considered, negative deviations of the flank angle of the short flank of the pin thread should be avoided, and preference should be given to positive ones. Negative relative deviations of both flanks usually worsen the fatigue strength of the pin due to the "wedge" effect. Types of deviations have been found that significantly increase fatigue strength and have an “anti-wedge” effect or equalize the load in the thread. They need detailed studies and can be the basis for optimizing the values of flank angle deviations on each turn.

Study on advanced assembly characteristics of locking with radial anti-loosening precision locked-nut while maintaining the design rigidity under dynamic precision fastening system

The rigidity of the precision fastening system is often reduced due to dynamic vibration after design assembly rigidity. Without an anti-loosening mechanism, it may even be completely loosened in severe cases. It is often used in the advanced assembly of important precision components or important precision transmissions, what is can keep the stable design dynamic rigidity. The relative fixation of the mechanism, due to the reduction of structural rigidity, often leads to problems such as reduced use accuracy, difficulty to grasp the vibration frequency, and reduced service life. In this paper the clamp locking precision locked-nut that is commonly used in precision fastening systems under dislocation vibration. Through the experiment of the forced dislocation vibration environmental factors to discuss the axial force is affected. To achieve the advanced assembly under keeping the stable design dynamic rigidity of the precision fastening system during dynamic use. In this paper, Assembling the clamp locking precision locked-nut on the precision system are simulated of the conditions, and the experimental target axial forces are 3000N, 5000N, and 7000N, respectively. The designed rigidity after forced dislocation vibration under the advanced assembly characteristic equation is achieved. And using various precision instruments is to measure the microscopic shape and geometric changes before and after the experiment. These are including the deflection of the end face of the nut, flatness, thread angle and thread surface roughness, etc. To grasp changes of relevant dynamic characteristics, and the assembly prediction equation of the target axial force is established. The results can be regarded as an important assembly basis for machine tools, automation, precision electronic special machines, aerospace industry, etc., to improve the dynamic accuracy and stability of their related precision fastening systems.

A Novel Screw Modeling Approach to Study the Effects of Screw Parameters on Pullout Strength.

Screw loosening remains a prominent problem for osteoporotic patients undergoing pedicle screw fixation surgeries and is affected by screw parameters (e.g., diameter, pitch, and thread angle). However, the individual and interactive effects of these parameters on screw fixation are not fully understood. Furthermore, the current finite element modeling of a threaded screw is less computationally efficient. To address these issues, we (1) explored a novel "simulated threaded screw" approach (virtual threads assigned to the contact elements of a simplified screw) and compared its performance with threaded and simplified screws, and (2) examined this approach the individual and interactive effects of altering screw diameter (5.5-6.5 mm), pitch (1-2 mm) and half-thread angle (20-30 deg) on pullout strength of normal vertebrae. Results demonstrated that the "simulated threaded screw" approach equivalently predicted pullout strength compared to the "threaded screw" approach (R2 = 0.99, slope = 1). We further found that the pullout strength was most sensitive to the change in screw diameter, followed by thread angle, pitch, and interactions of diameter*pitch or diameter*angle. In conclusion, the "simulated threaded screw" approach can achieve the same predictive capability compared to threaded modeling of the screw. The current findings may serve as useful references for planning of screw parameters, so as to improve the complication of screw loosening.

A 3-D finite element analysis of the effect of dental implant thread angle on stress distribution in the surrounding bone.

Background. This study aimed to evaluate the effect of an increase in fixture thread face angle on the amount and distribution of stresses in the surrounding bone of implants with four different thread shapes by three-dimensional finite element analysis. Methods. Eight different fixture designs, with v-shaped, buttress, reverse buttress, and trapezoid threads, and two face angles of 20 and 35 degrees, were modeled using a software program. Each model was affected by two static forces with different values and angles (200-N axial 0° force and 100-N 45° oblique force) to compare the distribution of stress in different fixture designs. Results. The maximum von Mises stress was detected in v-shaped threads. An increase in the angle of the threads to 35° significantly decreased maximum von Mises stress in cortical bone in v-shaped and reverse buttress threads; however, the von Mises stress in the trapezoid and buttress threads increased with an increase in the thread angle. Conclusion. Under the limitations of this study, although the shape of the thread and thread surface angle does not have a definite role in stress distribution in the bone surrounding the implant, they are effective in the amount and type of stress induced in the bone supporting the implant.

Interactive Effects of Five Dental Implant Design Parameters on the Peak Strains at the Interfacial Bone: A Finite Element Study.

The aim of this study was to evaluate and compare the effect of changing five macrostructural design parameters of dental implants on the peak strains experienced by the interfacial bone. Five geometric variables, including three body-related (implant length, diameter, and taper) and two thread-related (thread depth and thread angle) parameters, were defined. The alveolar bone was modeled as a block with anisotropic and linearly elastic properties with 20-mm height and 12-mm buccolingual and mesiodistal dimensions. Oblique occlusal loads (100-N vertical and 20-N horizontal) were applied to the abutment surface. A total of 162 models with different designs were defined by implementation of a full-factorial design. The peak values of the compressive and tensile principal strains in the cortical and cancellous bones were calculated by finite element analysis (FEA). Implant diameter and length had maximum and minimum effects on the peak compressive and tensile strains at the cortical interface, respectively. Implant diameter and thread depth had maximum and minimum effects on the maximum compressive strain at the cancellous interface, while thread angle and length had maximum and minimum significant effects on the maximum tensile strain at the cancellous interface. The interaction of thread parameters and taper has the greatest effect on the peak compressive and tensile strains at the cancellous interface and also on the peak tensile strain at the cortical interface, while body-related parameters are more effective on the peak compressive strain at the cortical interface.

Influence of thread parameters on the withdrawal capacity of wood screws to optimize the thread geometry

For wood screw connections, the withdrawal capacity is essential and is therefore an optimization target for wood screws. The withdrawal capacity is based on the composite action between the screw thread and the wood. Optimizing thread geometry requires knowledge of how thread parameters influence the withdrawal capacity. Up to now, this knowledge is largely unknown. Therefore, the objective is to determine the influence of thread height (1 mm; 1.48 mm), flank distance (3.04 mm; 6.08 mm), lead angle (6.8°; 13.6°), and thread angle (30°; 55°) on the withdrawal capacity. The influences are investigated for a tangential screw-in direction in spruce. For this, flat ribbed bars, so-called threaded test objects, are used. The effect on the withdrawal capacity is measured using an experimental setup based on test standard EN 1382 in two different planes of the flat thread to the wood fiber. 242 tests in RT plane and 286 in TL plane were analyzed with multifactorial analyses of variance. The thread height, flank distance, and thread angle show significant effects in both planes. A larger thread height, a smaller thread pitch, and a more acute thread angle increase the withdrawal capacity. Only in RT plane, a larger lead angle shows higher withdrawal capacity. The determined effects can be used to design the thread geometry of wood screws with higher withdrawal capacities. The accuracy of calculation models for the withdrawal capacity of wood screw connections can also be improved based on the findings. With the results, confirmation could be found for known models based on the theory of compression cones explaining the influences of the flank distance and thread angle.

Improvements to torque versus tension relationship considering nut dilation effects

Torque as a tightening method is a simple technique that can be used to tighten a bolt to a given pre-load. Therefore, it is important to theoretically derive an accurate torque vs tension relationship for threaded fasteners as this would enable the industry to achieve a reliable pre-load. Various attempts were made to develop a complete theoretical relationship between torque and tension. Due to the thread angle there exists a nut dilation force causing the nut to expand radially out wards. This effect is more prominent in nuts with smaller height (Style 0 hex nut, refer ISO 4035 1 ). This nut dilation force creates a combined frictional effect with the drive torque thus affecting the torque tension relationship. This paper proposes a novel 3D formulation for torque tension relationship taking into consideration the nut dilation effect. This paper further develops new formulae for tightening and loosening torque, retaining torque, tension vs nut rotational angle relationship as well as formula for nut dilation force for both tightening and loosening.

Research on application of corner detection in thread vision measurement

With the rapid development of the automation field, automatic inspection of fasteners in the aviation field has become a top priority. It is precious to realize the fast measurement of important information in fastener production by non-contact. This paper aims to detect the optical image detection of the external thread angle of fasteners. We analyze the traditional Ramer algorithm’s contour segmentation steps in separating thread edge from thread bottom arc to obtain accurate thread angle size and thread bottom arc radius. And Harris algorithm is proposed to find corners again by comparison. Finally, using a discrete point curvature to verify the Harris algorithm’s accuracy in corner detection. Meanwhile, by comparing the edge fitted thread angle with the measured thread angle to verify the Harris algorithm’s reliability in corner detection.