Gear Shaping Research Articles

Novel Third-Order Correction for a Helical Gear Shaping Cutter Made by a Lengthwise-Reciprocating Grinding Process

Although the Isoform® lengthwise-reciprocating grinding process is considered as one of the most accurate methods for generating the tooth profile geometry of a helical gear shaping cutter, the tooth profile accuracy produced by the Isoform® with a straight cone grinding wheel is not accurate enough for high precision requirement. That is why the shaper cutter is used as a rough cutting tool for most cases. A third-order profile correction to the cone grinding wheel is proposed to increase the accuracy of the work gear profile. A novel topography is developed to schematically show the work gear tooth profile accuracy cut by a resharpened shaping cutter. The profile errors corresponding to the varied resharpening depth are shown in the topography with information of true involute form diameter and semitopping depth. The usable resharpening depth of the shaping cutter can be determined by this topography. The numerical result indicates that third-order correction reduces the profile error of the major cutter enveloping gear to submicro and extends the resharpening depth.

저층 트롤의 그물입구 형상과 소해 단면적

Estimation of the gear shape and cross section of sweep at mouth of a bottom trawl net was described and applied to the field experiments obtained with the Scanmar system. The shape of the trawl net from wingend to the beginning of codend was assumed to be part of an elliptic cone of which the cross section was ellipse, and that of the float rope be of form $y_f

Shrink fit design for precision gear forging dies

The usual way to shrink fit design for precision forging of gear dies is to use thick wall cylinder theory (analytical approach) assuming that bore diameter is equal to pitch diameter by neglecting actual gear tooth shape. For more accurate determination, finite element method (FEM) can be used. The actual stresses predicted by FEM are much higher than the analytical approach, so that the design of the gear shaped die is beyond the capability of the analytical approach. In this paper, analytical approach for dies with gear teeth is modified using FEM solution sets. FEM analyses results are verified by experiments. During experiments cylinder approach is observed to be inadequate for forging loads. An easy to use set of formula and nomograms for determination of sizes of die and ring, and radial interference are presented. The solution set is verified with experiments. Proposed equations can safely be used for shrink fit design of precision forging gear dies.

Profile correction of a helical gear shaping cutter using the lengthwise-reciprocating grinding method

Currently, the Isoform® lengthwise-reciprocating grinding process is considered the most accurate method for generating the tooth profile of a gear shaping cutter. However, despite improving the profile accuracy of the grinding shaper, the Isoform® ground helical shaping cutter, especially one with a small tooth number, still produces pressure angle, curvature and profile errors. Therefore, we propose a mathematical model to correct such errors and then validate the model numerically using the tooth profile of a cutter enveloping gear.

ANALYSIS AND DESIGN OF PINION WITH INNER HELICAL GEAR BY FEM

Cold forging of pinion gear with shape of outer spur gear and inner helical gear have been investigated in this study. A numerical analysis for preform design substituting cutting process in gear forging was developed by means of upsetting process. By using the finite element program DEFORM-3D, the analysis is carried out. Using this simulation, the preform of pinion and helical gear forging process were designed. The suggested process is verified by experiment. Compared to the traditional CNC processing, the upsetting process can form a preform without cutting, which leads to shorter forming time and reduce material usage.

Study on the Accuracy of Injection Molded Plastic Gear with the Assistance of Supercritical Fluid and a Pressurized Mold

Plastic gears are lighter and less noisy compared to steel gears, and they can be easily shaped into diverse forms by the injection molding process. For this reason, plastic gears are widely used in industry. An extensive amount of research has been conducted on gear materials and methods of shaping plastic gears for durability and for broader applications. In this article, the focus is on producing a plastic gear shaping method incorporating the injection molding process. The most important factor influencing the durability of a plastic gear is its accuracy. Unlike steel gears, the dimensions of plastic gears are subject to considerable change during formation, and this is due to certain conditions during the injection molding process and to the mold structure. The main causes of size variability here are the high viscosity of plastic and the shrinkage ratio of the resin. In our study, a supercritical fluid was used to reduce the viscosity of the plastic, and a pressurized mold was used to control the shrinkage ratio of the resin. Thus, production of an improved, more highly accurate plastic gear was achieved.

Numerical analysis and design of pinion with inner helical gear by FEM

In the design of the cold forging process one of the most important tasks is the determination of the required number of processes. Preforming in incremental steps is aimed at achieving high accuracy of the forged part, high quality of the surfaces and also decreasing the die damage during the forging process. Cold forging of pinion gear with shape of outer spur gear and inner helical gear have been investigated in this study. A numerical analysis for preform design substituting a cutting process in the gear forging was developed by means of upsetting process. By using the finite element (FE) program DEFORM-3D, the analysis is carried out. Using this simulation, the preform of the pinion and helical gear forging process was designed. The suggested valuable information regarding the forging process shows a successful attempt. The suggested process is verified by experiment. Compared to the traditional computer numerical control (CNC) processing, the upsetting process can form a preform without cutting, which leads to shorter forming time and reduced material usage.

Fundamental study of surface densification of PM gears by rolling using FE analysis

The complex shape of gears is very attractive to the near-net-shape PM technology. The strength of conventional PM parts is reduced by the residual porosity due to the power law relationship between the density and the mechanical properties. The maximum stresses in gears are found in the tooth root and the flank near or directly at the surface, so that by a local densification of the near surface layer the maximum load carrying capacity of the complete gear can be increased. This surface densification can be achieved by a rolling process. Due to the own elastic-plastic behavior of PM materials and due to the continuous change of the contact conditions during rolling, the process is too complex to be described analytically. To gain a better understanding of the process, the numerical simulation is a capable method. In this paper an FEA model is prepared and verified based on an experimental investigation. Additionally, case studies were carried out in order to analyze the relationship between the process parameters and the densification result.

폴리머 몰드를 이용한 금속 나노분말의 미세부품 제조

Novel polymer mold process for fabrication of microcomponents using metal nanopowders was developed and experimentally optimized. Polymer mold for forming green components was produced by using a hard master mold and polydimethylsiloxane (PDMS). In the preparation of metallic powder premix for the green components without any defect, 90 wt.% 17-4PH statinless steel nanopowders and 10 wt.% organic binder were mixed by a ball milling process. The green components with very clear gear shape were formed by filling the powder premix into the PDMS soft mold in surrounding at about <TEX>$100^{\circ}C$</TEX>. Cold isostatic pressing (CIP) was very potent process to decrease a porosity in the sintered microcomponent. The microgear fabricated by the improved process showed a good dimension tolerance of about 1.2%.

Ensuring accuracy of cylindrical toothed gear wheels at production design

1 One of the efficient methods of ensuring the accuracy of machine element processing is design of processes of their production on the basis of regularities of stage-by-stage variation and forming of accuracy parameters (blank quality, element design, state of equipment and auxiliaries, and so on). Unfortunately, this approach is seldom applied at present in the practice of machine engineering. One of the reasons is the erroneous, although widely spread, opinion that element accuracy is formed mainly at the final processing. Moreover, mathematical models of many processes of machine element processing are lacking. For mathematical modeling of the variation and forming of accuracy parameters of cylindrical toothed gear wheels (CTGW) during their production, extensive experimental studies were carried out by us. The variation of the accuracy parameters of teeth and CTGW base surfaces at basic processing operations and the influence of the accuracy of base surfaces and cutting modes on tooth accuracy at gear milling and shaping were studied. In the framework of this problem, stage-by-stage variation of eleven accuracy factors of teeth and five accuracy factors of CTGW base surfaces of tractors, auto trucks, and metal-cutting machines (module m = 2‐5 mm; number of teeth 23‐51; material steels 45, 40Kh, 25KhGT, 20KhN3A, 18KhGT, and so on) after eight processing operations of tooth processing and eleven operations of base surface processing under industrial and laboratory conditions were studied experimentally. The following technological processes (TP) were studied: shaving on rigid and expanding mandrels and chemical‐thermal processing (CTP)—cementation and nitrocementation in muffleless aggregates, gear burnishing, gear honing, gear grinding by conical and worm wheels, bore processing (including drilling; core drilling; single- and double-broaching; honing; burnishing; grit blasting; CTP; and rough, half-rough, and finish turning), as well as CTP and ring gear grinding. 1 Based on Proceedings of the International Scientific-Technical Conference “Improvement of Machine Quality at Stages of Their Lifetime,” Bryansk, 2005. In the course of the studies, 65 batches of CTGW were processed and measured under production conditions and 15 batches under laboratory conditions; the size of each batch was N = 50‐100 pieces. About 90% of the CTGW dimension types manufactured in auto, tractor, and machine-tool construction in the Republic of Belarus were covered. The processing of the experimental data showed the appropriateness of the application of correlationregression analysis for modeling the stage-by-stage variation of the CTGW accuracy parameters on the basis of measurement of one sample of sufficient volume. For this purpose, among other things, the accuracy parameter distributions (192 distributions were studied) and the stationary character and ergodicity of the considered TP for the chosen parameters were analyzed. Moreover, phase analysis of the variation of the CTGW kinematical accuracy factors for different types of gear treatments was carried out. Some results of research characterizing the phenomenon of technological heredity at variation of CTGW accuracy parameters during their processing and the possibility of modeling stage-by-stage correlations of these parameters for the considered processing operations are given in Tables 1‐3 (the data on tooth accuracy parameters according to GOST 1643-81 are given in Table 1, the accuracy parameters of mounting bores are given in Table 2, and the accuracy parameters of ring gear ends are given in Table 3). It was established that, for most CTGW accuracy parameters and their processing operations, technological heredity takes place, since r xy > 0.273, B > 10%, where r xy is the pair correlation coefficient between the values of this parameter ( x ) before and ( y ) after the considered operation, and B is the variance of the value of y from the previous operation. The analysis of results obtained in the present studies and those carried out earlier provided the possibility of assuming that the dependences y = f ( x ) can be described by first or second order polynomials,

Fabrication of Micro Spur Gear in Nano Grained Al Alloy

In present work, manufacturing technologies of micro parts by micro forging and pressing were studied using strain softening phenomenon in nano grained Al-1.5mass%Mg alloy. During compressive test at 300, the Al alloy showed stain softening phenomenon by grain boundary sliding regardless of strain rate. Micro spur gear with ten teeth (height of 200 μm and pitch of 250 μm) was fabricated with sound shape by micro forging. During micro forging, increase of applied stress induced by friction between material and die surface was effectively compensated by decrease of stress by strain softening behavior and as a result, flow stress increased only about 50 MPa more than that in compressive test. However, in micro pressing, flow of material did not occurred sufficiently to fill die and the resultant shape of gear was very poor.

A method for estimating the gear shape of a mid-water trawl

An estimation of the shape of the gear (gear shape) during a mid-water trawl and the angle of attack of a cambered otter board can be achieved by implementing a three-dimensional semi-analytical treatment of the towing cable (warp) of a trawl system. This can be achieved by processing the field data obtained using the Scanmar system. The shape of the hand rope, bridles and head (or foot) rope attached behind the otter boards in a horizontal plane was assumed to be a function of the form y r = A x r B . The distance between otter boards (otter board spread) estimated using the three-dimensional analysis of a towing cable system should be equal to that obtained using the functional equation. The shape of a trawl net from wing end to bag net was assumed to be of the form x 2 / a e 2 + y 2 / b e 2 = ( z - c ) 2 / c 2 , i.e., as part of an elliptic cone. The volume covered by the trawl net, the ratio of vertical radius to horizontal radius of the ellipse, the contribution of the side panel to net height and the inclination angle of the head rope (float line) according to towing speed were obtained. The angle of attack of a cambered otter board could be obtained by calculating the equilibrium of forces and moment around the otter board.

Numerical computing method of noncircular gear tooth profiles generated by shaper cutters

A simple and accurate numerical method was proposed for calculating the tooth profile of a noncircular gear. This method is directly based on the real gear shaping process, rather than deducing and solving complicated meshing equations used in the traditional method. The tooth profile is gradually obtained from the boundary produced by continuously plotting the cutter profile on the gear transverse plane. The key point of the method is picking up the graph boundaries. The relative position of the cutter profile on the gear transverse plane is determined by the given pitch line of the noncircular gear, parameters of the shaper cutter, and the shaping process data. In comparison with the traditional method, it is universal and is much more efficient and accurate, especially for noncircular gears, which have nontrivial pitch lines. Special problems in gear design and manufacturing, such as tooth pointing, undercut, and fillet interference, are included in the process. As an application example of the numerical method, a square internal gear is chosen from a new type of hydraulic motor with noncircular planetary gears, and the tooth profile of that gear is computed. The gear is successfully machined by electromagnetic discharge (EMD) using the resulting data.

Three-dimensional underwater shape measurement of tuna longline using ultrasonic positioning system and ORBCOMM buoy

The installation depth of the hook in longline fishing gear has previously been measured with micro depth loggers. Research that assumes the catenary shape of longline fishing gear by a simulation based on these data has been done. However, it was not known whether the branch line was tangled with the main line or flowed with the current. In this research, an ultrasonic positioning system generally used to investigate the underwater behavior of marine organisms, and a buoy with a communications satellite, have been used, and the 3-dimensional underwater shape of tuna longline fishing gear was measured. It was possible to monitor changes in fishing gear in real time. The possibility of high precision measurement was suggested with future technical improvement.

2218 平歯車とかみ合う内歯コニカルギヤの設計法(OS1-10 コニカルギヤ)

In this study, we call an internal gear having conical angle as the internal conical gear. In the case of conjugating with spur gear, this gear can transmit rotational motion between intersecting shafts. Also in the case of conjugating with conical gear, there is possibility of adjusting backlash by axial movement. Therefore, as a first step of the study we obtain theoretical tooth surface of the internal conical gear cut by gear shaper. Next we measured tooth surface of the test gears and compared them with theoretical one. Finally the tooth-bearing test confirms that theoretical analyses holds true.

Dynamic simulation of tuna longline gear using numerical methods

The underwater shape and hook depth of tuna longline gear are important factors determining fishing performance. In this study, how the shape of tuna longline gear changes in response to sea conditions and gear rigging is explained. Physical models of underwater gear shape were made to simulate fishing gear and analyzed according to the direction and velocity of currents. Then experiments with small-scale models were conducted in a flume tank to confirm the accuracy of the simulation analysis. Finally, the simulation was examined relative to actual longline fishing gear. This approach provided an improvement over previous analytical methods that did not consider fishing gear shape in response to different sea conditions. A useful result is an improved understanding of the relationship between ocean currents and the configuration of longline gear (the shortening ratio, and number of hooks per basket). These factors affect hook depth which, in turn, affects selectivity. Application of these results could lead to more effective and efficient fishing under different sea conditions.

A study on the cold ironing process for the drum clutch with inner gear shapes

This paper describes a 3D FE simulation of the cold ironing process for forming the drum clutch, the main part component of the automatic transmission. The process of the drum clutch with inner gears that was employed in this study consists of 12 steps associated with nine deep drawing processes and three ironing processes to form the inner gear shape. The ironing processes were focused on this study in order to estimate the dimensional accuracy of the inner gear shape according to the process variables such as the punch shape, the approach angle of the punch, and the thickness reduction ratio. A rigid-plastic finite element simulation was applied to analyze the deformation characteristics of the ironing processes and to determine the optimum parameter for selected conditions. Finally, an experiment on the whole drum clutch forming process was carried out to examine the validity of the analytical results and the chosen parameters.

Designing Method of Concave Conical Gear by Gear Shaper (2nd Report, Principal Normal Radii, Allowable Normal load, and Design of a Pair of Gears)

Theoretically, the contact between tooth surfaces of a pair of conical involute gears is the point contact. Hence the tooth surface durability is generally small. “Concave conical gear” was invented in order to overcome this weak point. The 1st report proves that this gear can be cut by tilt-type gear shaper. In this paper, first the principal normal radii at the pitch point are obtained. Secondly, an allowable normal load of a pair of concave conical gears that cut by this method is obtained, which could be larger than that of a pair of conical involute gears. Finally, the designing method of a pair of concave conical gears cut by this method is presented.

布基材フェノール樹脂積層材料を用いた動力伝達用歯車の疲労強度の算定法(O.S.09-3 プラスチック歯車(3))

In this research, a laminate material (a phenolic resin reinforced by plain woven cotton cloth) was used for the gear material. The gear was produced by hobbing. In this paper, we addressed the bending strength of gear teeth in the basic design process. First, Vibration characteristics between metal gear and metal gear and cotton fiber-reinforced plastic gear and metal gear when the gears meshed are compared. Second, bending fractures in teeth, were examined by a line load applied to the tooth root fillet and tooth breakage in this area during bending was investigated. Third, to investigate the repetition fatigue strength of teeth, a fatigue test was performed. Forth, tension, uniaxial compression, 3-point and 4-point bending, and shearing tests were performed for the gear materials used in order to investigate the destruction strength of the gear shape and the primary factors in the destruction form.

다랑어 연승어구의 형상에 관한 시뮬레이션

다랑어 연승어구의 형상에 관한 시뮬레이션