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Objective To investigate the feasibility of using Cariostat test for caries risk assessment in adult outpatients and provide a reference basis for caries prevention and treatment in adult outpatients of different ages. Methods Fifty-two adult patients of different ages (18-24, 25-34, 35-44, 45-54, and ≥55 years old) attending outpatient clinics of The Affiliated Stomatological Hospital of Nanjing Medical University were tested for caries activity using the Cariostat test. Oral examinations were conducted according to the criteria of the 5th edition of the Basic Methods of Oral Health Surveys of the World Health Organization, and on-site questionnaire surveys were performed for the Cariogram assessment system. Oral examinations included assessments of dental arch conditions and caries status, while questionnaire surveys covered dietary habits, oral health care habits, etc. The caries status of adult outpatients of different age groups was analyzed, and caries activity was assessed using the Cariostat test. The caries risk levels were determined, and the consistency between the Cariostat test and the Cariogram assessment system was evaluated. Results It was found that there was a difference in mean decayed, missing and filled surfaces (DMFS) between the low-risk group of adult outpatients with different caries risk levels classed by the Cariostat test and the intermediate and high-risk groups (P

Abstract Background Although laparoscopic hepatectomy (LH) and radiofrequency ablation (RFA) are the 2 principal minimally invasive surgical approaches and the first line of treatments for patients with hepatocellular carcinoma (HCC). It is not clear which one has greater safety and efficacy. In this meta-analysis, we aim to compare the safety and effectiveness of LH versus RFA for patients with HCC, especially where perioperative and postoperative outcomes differrent. Methods In PROSPERO, a meta-analysis with registration number CRD42021257575 was registered. Using an established search strategy, we systematically searched Web of Science, PubMed, and Embase to identify eligible studies before June 2023. Data on operative times, blood loss, length of stay, overall complications, overall survival (OS) and recurrence-free survival (RFS) were subjected to meta-analysis. Results Overall, the present meta-analysis included 8 retrospective and 6 PSM studies comprising 1,848 patients (810 and 1,038 patients underwent LH and RFA). In this meta-analysis, neither LH nor RFA showed significant differences in 1-year and 3-year OS rate and 5-year RFS rate. Despite this, in comparison to the RFA group, LH resulted in significantly higher 1-year(p

Summary: Hepatectomy is widely considered a potential treatment for hepatocellular carcinoma (HCC). Unfortunately, one-third of HCC patients have tumor recurrence within 2 years after surgery (early recurrence), accounting for more than 60% of all recurrence patients. Early recurrence is associated with a worse prognosis. Previous studies have shown that microvascular invasion (MVI) is one of the key factors for early recurrence and poor prognosis in patients with HCC after surgery. This paper reviews the latest literature and summarizes the predictors of MVI, the correlation between MVI and early recurrence, the identification of suspicious nodules or subclinical lesions, and the treatment strategies for MVI-positive HCC. The aim is to explore the management of patients with MVI-positive HCC.

Abstract Background The prognostic predictive tool for patients with colorectal liver metastasis (CRLM) is limited and the criteria for administering preoperative neoadjuvant chemotherapy in CRLM patients remain controversial. Methods This study enrolled 532 CRLM patients at West China Hospital (WCH) from January 2009 to December 2019. Prognostic factors were identified from the training cohort to construct a WCH‐nomogram and evaluating accuracy in the validation cohort. Receiver operating characteristic (ROC) curve analysis was used to compare the prediction accuracy with other existing prediction tools. Results From the analysis of the training cohort, four independent prognostic risk factors, namely tumor marker score, KRAS mutation, primary lymph node metastasis, and tumor burden score were identified on which a WCH‐nomogram was constructed. The C‐index of the two cohorts were 0.674 (95% CI: 0.634–0.713) and 0.655 (95% CI: 0.586–0.723), respectively, which was better than the previously reported predication scores (CRS, m‐CS and GAME score). ROC curves showed AUCs for predicting 1‐, 3‐, and 5‐year overall survival (OS) of 0.758, 0.709, and 0.717 in the training cohort, and 0.860, 0.669, and 0.692 in the validation cohort, respectively. A cutoff value of 114.5 points was obtained for the WCH‐nomogram total score based on the maximum Youden index of the ROC curve of 5‐year OS. Risk stratification showed significantly better prognosis in the low‐risk group, however, the high‐risk group was more likely to benefit from neoadjuvant chemotherapy. Conclusions The WCH‐nomogram demonstrates superior prognostic stratification compared to prior scoring systems, effectively identifying CRLM patients who may benefit the most from neoadjuvant chemotherapy.

With the rapid development of “Internet of Things” and human-computer interaction techniques, it is essential and urgent to develop facile and scalable fabrication platforms for stretchable flexible sensor. Herein, we report a facile strategy of using the green choline chloride–acrylamide deep eutectic solvent (CC-AM DES) to guide the in-situ ring-opening polymerization of α-lipoic acid (LA), leading to the successful development of a stretchable ionogel material. The as-prepared ionogel from CC-AM DES system exhibits multifunctional merits including the super stretchability (>9000%), 100% UV-blocking ability, tunable adhesiveness (29–414 kPa), high ionic conductivity (4.45 × 10−4 S/cm), and ideal anti-freezing (–27 °C). In addition, this outstanding ionogel can be readily coated on various material substrates with designable shapes and patterns. Owning to these promising properties and performances, a scalable flexible strain sensor is assembled from the ionogel and exhibits stable resistance variations (R/R0) towards multiple external mechanical stimulus. This study provides a green, cost effective, and scalable strategy to fabricate ionogel materials and multifunctional flexible strain sensors, showing a great potential in the fast-emerging highly stretchable wearable/flexible electronics.

This paper presents a method of calculating and correcting grinding face gears on an internal gear grinding machine. The generating principle of face gears is studied, and the feasibility of grinding motion on an internal gear grinding machine is analyzed. Then, the motions that need to be followed for grinding are analyzed based on the gear machine tool structure. Four main error sources causing tooth surface deviation in the grinding movements are proposed. The mathematical modeling of the grinding of face gears containing proposed error sources on an internal gear grinding machine is accurately established. The influence of the error sources on the topological deviations of the tooth surface is explored. A sensitivity matrix is established for the influence of various error factors on the tooth surface deviations. The correction values of each error factor are obtained in the case of existing tooth surface deviations. Finally, a virtual machining experiment is conducted, which proves the accuracy of the proposed method for characterizing grinding and realizing corrections.

While machining spiral bevel gear by forming method, the stability of cutting force acts a significant element affecting tool wear and machining performance. Based on the actual tooth-cutting situation, the calculation model of multi-blade cutting force is set up, and a new method to improve the machining precision of the tooth surface by using equal cutting force machining is put forward herein. Using the principle of forming method and the established machining model, the real-time tool-tip height is calculated, and the cutting area calculation formula is derived. The dynamic cutting force during multi-blade cutting is calculated by adopting the bevel-cutting model. Taking the cutting area at the most cutting force as the target cutting area, calculating equal cutting area is achieved by calculating the real-time feed rate, thereby achieving equal cutting force feed, and finally the calculation and improvement of cutting force during the machining of spiral bevel gears by the forming method are realized.

Face gear transmission is the transmission mechanism composed of cylindrical gear and face gear. At present, the tooth making method of face gear is still tooth cutting, with low material utilization and low production efficiency. The metal streamlines are cut off, resulting in low fatigue strength of gear teeth. In this paper, the forming of hot rolling was numerically simulated, with which the characteristics of equivalent stress field, equivalent strain field, rolling force variation, and metal flow in the process of rolling were analyzed. Finally, a hot rolling experimental device was set up, by which the face gear test piece was rolled. Then its tooth surface precision was investigated. The research reveals that hot rolling spur face gears is technological feasible and has promising prospects in industrial applications.

Spiral bevel gears are manufactured and used in pairs. When one part usually pinion fatigued, the pair will be replaced. It inevitably leads to a waste of resources and time. To solve this phenomenon, a method to remanufacture pinion with ease-off topology modification is proposed. First, the wheel and pinion were measured to fitting tooth surface, and then a conjugate surface of wheel fitting tooth surface was derived. Secondly, an ease-off topology surface was superimposed to the conjugate surface to improve mesh performance, and then a design tooth surface was obtained. Thirdly, a mathematical model to process pinion was established and original machine-tool settings parameters of pinion were calculated. The deviations between design and original tooth surface of pinion were count, and an error correction model of tooth surface was established to adjust machine-tool settings parameters. Finally, an experimental verification was conducted. The pinion was remanufactured by a face-milled generator and the mesh performance was consistent with design. The result demonstrates the method proposed is effectiveness and feasible. It provides reference for the remanufacture of large-size spiral bevel gears and has good value for engineering application.

The warm-forging technology of the spiral bevel gear (873 K–1073 K) was studied. Based on the rigid–plastic finite element method, a numerical simulation was carried out by using DEFORM V11.0 software to explore the influence of different process parameters on gear-forming quality and forming force in the process of warm forging. Taking into account the complexity of the geometry of spiral bevel gears and the diversity of the influence factors in the forging process, as determined through nine groups of numerical simulation experiments, this paper systematically analyzed the influence law of different forging speeds, die preheating temperatures, friction factors and workpiece heating temperatures on the effective stress and strain of spiral bevel gears. The best combination of process parameters with minimum forging force was obtained via the orthogonal experiment, which provides a theoretical basis for the optimization design of the precision forging process of spiral bevel gears and also provides a new idea for studying the precision-forging–forming process of other complex parts.

Aiming at the same batch of spiral bevel gears with the same gear material， NC milling method and heat treatment specification， a bootstrap resampling is carried out on a small number of tooth surface deviation sample data based on the bootstrap method， a large number of sample data are obtained and a bootstrap statistical model of batch spiral bevel gear tooth surface deviation is established； the probability characteristic value of the sequential points of tooth surface measurement is calculated， and whether they conform to the normal distribution is tested by k-s； the estimated true value， estimated interval and other parameters are selected to describe their statistical laws and results； through the cubic NURBS surface fitting method， the variation law of the tooth surface deviation of the whole batch is obtained， and the effective evaluation of the tooth surface accuracy of the whole batch is realized. The bootstrap statistical model provides a theoretical basis for guiding the modification of tooth surface processing parameters and efficient and stable production.

Abstract Background The prognostic value of sarcopenia in combined hepatocellular carcinoma and cholangiocarcinoma (cHCC‐CC) patients after surgery has not been evaluated, while the efficacy of the available tumor stage for cHCC‐CC remains controversial. Methods All consecutive cHCC‐CC patients after surgery were retrieved. The patients were stratified by the sex‐specific medians of the psoas muscle index into groups with or without sarcopenia. Prognosis was analyzed using the Kaplan–Meier (K–M) method, and the K–M curves were adjusted by inverse probability weighting (IPW). A nomogram based on Cox regression analysis was established and further compared with primary liver cancer (PLC) stages by internal validation based on bootstrap resampling and k‐fold cross‐validation. Results A total of 153 patients were stratified into sarcopenia and non‐sarcopenia groups. The sarcopenia group revealed statistically worse overall survival (OS) and disease‐free survival (DFS) using the K–M method and K–M curves adjusted by IPW. Multivariate Cox regression analyses suggested sarcopenia as an independent risk factor for OS (HR = 1.55; p = 0.040) and DFS (HR = 1.55; p = 0.019). Subgroup analysis based on baseline variables showed sarcopenia as a stable risk factor for the prognosis. Our nomogram outperformed PLC stages in prognostic prediction, as evidenced by the best c‐index, area under the curve, and positive improvement of the net reclassification index and integrated discrimination improvement. A fivefold cross‐validation revealed consistent results. Decision curve analysis revealed higher net benefits of the nomogram than PLC stages. Conclusions Sarcopenia is an independent and stable risk factor for the prognosis of cHCC‐CC patients after surgery. Our nomogram might aid high‐risk patient identification and clinical decisions.

Abstract Lipid metabolic reprogramming is one of the important metabolic characteristics of cancer cells. As major components of lipids, fatty acids provide energy and material basis for cancer cell survival. Abnormal fatty acid metabolism has been found in many cancers. Fatty acid uptake, transport, and synthesis are closely related to the pathogenesis of cancer. Meanwhile, fatty acid changes in the membrane structure of cancer cells and signal transduction mediated by signaling lipids are also helping cancer cells survive in the changing microenvironment. Some of these enzymes and metabolites involved in fatty acid metabolism are emerging as unique cancer biomarkers. Multiple studies have shown that disordered fatty acids can regulate tumor cell proliferation, metastasis, and drug resistance. Therefore, targeting fatty acid metabolism has become a promising treatment strategy. Here, we mainly present metabolic alterations of fatty acids, the basic components of lipids, in cancer. We discuss the cancer treatment based on fatty acid and fatty acid metabolism. These may provide a basis for a better understanding of lipid metabolic reprogramming in cancer, and also provide new ideas for cancer biomarker search, drug development, and combination therapy.

Non-Hermitian skin effect (NHSE), where huge modes are accumulated at system boundaries, offers new possibility for steering the transport and localization of light by non-Hermiticity. Here, the direction-dependent NHSE is proposed in a photonic waveguide array via spatially complex modulation, where the skin modes tend to localize at different boundaries for opposite propagation directions. We utilize complex modulation to arouse anisotropic coupling between symmetric and anti-symmetric modes in multimode waveguides and further match the refractive index of adjacent waveguides. In this way, a non-Hermitian Su–Schrieffer–Heeger (SSH) lattice that supports NHSE is achieved. In particular, the anisotropic coupling is highly unidirectional. For forward direction, it allows mode conversion from antisymmetric modes to symmetric modes. However, the process is forbidden for backward direction. As a result, the skin modes tend to locate at lower boundary for forward propagation but the localization direction is reversed for backward injection. Our results provide a potential platform to investigate NHSE on photonic chips and may find applications in non-magnetic unidirectional devices.

Global Navigation Satellite System (GNSS) observations are subject to various errors during their propagation process. A reasonable correction of these errors can improve the positioning, navigation, and timing (PNT) service capability. The impact of multipaths on pseudorange observations can reach a decimeters or even meters level. However, their mechanism is complex and there is currently no universally accepted high-precision correction model. The correlation between the pseudorange multipaths (MP) of BDS-2 satellites and satellite elevation has been confirmed, while there have been fewer analyses of the MP characteristics for different frequencies of BDS-3 satellites. The broadcasting of multi-frequency observations in BDS-3 should theoretically make the extracted MP more accurate compared to traditional methods. Based on this, in this contribution, a multi-frequency MP extraction algorithm based on the least squares principle is proposed, which can simultaneously eliminate the influence of higher-order ionospheric delay. The analytical expression for only eliminating first-order ionospheric delay is successfully derived. Subsequently, the characteristics of the MPs extracted from different frequency combinations and the impact of combination noise on the extraction accuracy are discussed. The influence of second-order ionospheric delay on the MPs for each frequency under different combination noises, as well as the periodic behavior exhibited in long-term observations of the BDS-3 medium earth orbit (MEO) and inclined geosynchronous orbit (IGSO) satellites, are also analyzed. Finally, the correlations between the MPs of each frequency of BDS satellite and elevation are quantitatively analyzed based on observations from 35 stations. Overall, this work has positive implications for the study of the MP characteristics of BDS-3 and subsequent modeling efforts.

Abstract Background Roses are famous ornamental plants worldwide. Floral coloration is one of the most prominent traits in roses and is mainly regulated through the anthocyanin biosynthetic pathway. In this study, we investigated the key genes and metabolites of the anthocyanin biosynthetic pathway involved in color mutation in miniature roses. A comparative metabolome and transcriptome analysis was carried out on the Neptune King rose and its color mutant, Queen rose, at the blooming stage. Neptune King rose has light pink colored petals while Queen rose has deep pink colored petals. Result A total of 190 flavonoid-related metabolites and 38,551 unique genes were identified. The contents of 45 flavonoid-related metabolites, and the expression of 15 genes participating in the flavonoid pathway, varied significantly between the two cultivars. Seven anthocyanins (cyanidin 3-O-glucosyl-malonylglucoside, cyanidin O-syringic acid, cyanidin 3-O-rutinoside, cyanidin 3-O-galactoside, cyanidin 3-O-glucoside, peonidin 3-O-glucoside chloride, and pelargonidin 3-O-glucoside) were found to be the major metabolites, with higher abundance in the Queen rose. Thirteen anthocyanin biosynthetic related genes showed an upregulation trend in the mutant flower, which may favor the higher levels of anthocyanins in the mutant. Besides, eight TRANSPARENT TESTA 12 genes were found upregulated in Queen rose, probably contributing to a high vacuolar sequestration of anthocyanins. Thirty transcription factors, including two MYB and one bHLH, were differentially expressed between the two cultivars. Conclusions This study provides important insights into major genes and metabolites of the anthocyanin biosynthetic pathway modulating flower coloration in miniature rose. The results will be conducive for manipulating the anthocyanin pathways in order to engineer novel miniature rose cultivars with specific colors.

Abstract Background There is still some debate as to whether transcatheter arterial chemoembolization (TACE) plus radiofrequency ablation (RFA) is better than TACE or RFA alone. This meta-analysis aimed to compare the efficacy and safety of TACE plus RFA for hepatocellular carcinoma (HCC) with RFA or TACE alone. Methods We searched PubMed, MEDLINE, Embase, Cochrane Library, and CNKI (China National Knowledge Infrastructure) for all relevant randomized controlled trials and retrospective studies reporting overall survival (OS), recurrence-free survival (RFS), and complications of TACE plus RFA for HCC, compared with RFA or TACE alone. Results Twenty-one studies involving 3413 patients were included. TACE combined with RFA was associated with better OS (hazard ratio [HR]=0.62, 95% confidence intervals [CI] = 0.55–0.71, P < 0.001) and RFS (HR = 0.52, 95% CI = 0.39–0.69, P < 0.001) than TACE alone; compared with RFA alone, TACE plus RFA resulted in longer OS (HR = 0.63, 95% CI = 0.53–0.75, P < 0.001) and RFS (HR = 0.60, 95% CI = 0.51–0.71, P < 0.001). Subgroup analyses by tumor size also showed that combined treatment resulted in better OS and RFS compared with RFA alone in patients with HCC larger than 3 cm. Combined treatment resulted in similar rate of major complications compared with TACE or RFA alone (OR = 1.78, 95% CI = 0.99–3.20, P = 0.05; OR = 1.00, 95% CI = 0.42–2.38, P = 1.00, respectively). Conclusions TACE combined with RFA was more effective for HCC than TACE alone. For patients with a tumor larger than 3 cm, the combined treatment also achieved a better effect than RFA alone.

The Flange fork is a key part of automobile axle， and the machining accuracy of its end face tooth affects the reliability of axle and even the whole vehicle. The calculation and processing technology of end face tooth surface of the flange york are researched. In order to realize the measurement and correction of the tooth surface based on the measuring machine， the theory of tooth surface calculation and deviation correction is constructed. An example is introduced to realize the machining simulation of the tooth surface of the flange york， and the accuracy of tooth surface calculation is verified by comparing the gouge and excess amount of theoretical tooth surface and simulated tooth surface. The experimental processing of the end face tooth surface of the flange york is carried out， which verifies the correctness of the tooth surface correction theory， and theoretical reference for the processing of the end face tooth surface of the flange york is provided.

A mathematical model is established to machine spiral bevel gears by duplex helical method. Based on the meshing principle of the gear， the digital representation of the spiral bevel gear tooth surface processed by the double helix method and the construction of discrete tooth surface points are completed， and the influence degree of each machine parameter error on tooth surface topology structure are analyzed. The correction model of tooth surface is built， through numerical example verification， the results show that tooth surface deviation is reduced effectively.

To improve the machining efficiency of face gears, a novel efficient machining method referred to as power skiving is applied to the machining of face gears and is presented in this paper. The processing principle of machining face gears by power skiving and the relative motion between the cutting tool and the face gears is discussed. Then, the mathematical models of the power skiving cutter with a fillet angle and the machining process by power skiving are established. The tooth flank equation of the face gears using the new processing method is derived. To describe the tooth flank structure, the difference between the tooth flank of power skiving face gears and traditional face gears, in which the surface is obtained by involute cylindrical gears, is compared, and a tooth flank contact analysis is conducted. The feasibility of the new processing method and the correctness of the mathematical model are verified by a power skiving experiment conducted on the face gear drive of a six-axis machine tool. Finally, the influence rule of the skiving cutter parameters on the meshing performance is analyzed in the process of machining face gears, and guidance is provided for the parameter design of power skiving cutting tools for face gears.

BackgroundRobotic distal pancreatectomy (RDP) and laparoscopic distal pancreatectomy (LDP) are the two principal minimally invasive surgical approaches for patients with pancreatic body and tail adenocarcinoma. The use of RDP and LDP for pancreatic ductal adenocarcinoma (PDAC) remains controversial, and which one can provide a better R0 rate is not clear.MethodsA comprehensive search for studies that compared robotic versus laparoscopic distal pancreatectomy for PDAC published until July 31, 2021, was conducted. Data on perioperative outcomes and oncologic outcomes (R0-resection and lymph node dissection) were subjected to meta-analysis. PubMed, Cochrane Central Register, Web of Science, and EMBASE were searched based on a defined search strategy to identify eligible studies before July 2021.ResultsSix retrospective studies comprising 572 patients (152 and 420 patients underwent RDP and LDP) were included. The present meta-analysis showed that there were no significant differences in operative time, tumor size, and lymph node dissection between RDP and LDP group. Nevertheless, compared with the LDP group, RDP results seem to demonstrate a possibility in higher R0 resection rate (p

The driving performance of low-noise and high-strength spiral bevel gears（include spiral bevel gear and cycloid bevel gear） is required to be improved by advanced equipment. Through tooth surface topology design to improve the stiffness and bearing capacity，reduce vibration noise and the sensitivity of installation error is a research hotspot at present. The development of spiral bevel gear tooth surface topology design is briefly introduced，the basic principle of the latest tooth surface design is discussed，and the characteristics are analyzed. The reference is provided for the tooth surface design of high performance spiral bevel gears.

In this paper a method to calculate machine tool setting parameters for spiral bevel gars by duplex helical method is proposed, in which contact path is predesigned. Firstly, machine setting parameters and curvature parameters in reference points of gear are calculated; secondly, curvature parameters of technology and cut in reference points of pinion are calculated based on meshing theory; then, machine tool setting parameters of pinion are calculated on the basic of the relationship of curvature parameters of technology and cut. Mathematic models of tooth contact analysis and ease-off topology are established to check out the machine tool setting parameters. An example is presented that machine tool setting parameters are calculated based on the method proposed in this paper, which predesign contact paths are 45°, 60°, and 70° respectively. The contact path of TCA results exist errors are less than 0.5% comparing to predesign; the results achieve the design requirement. Finally a cut experiment is carried out which the predesign of contact path is 70°; the results of rolling test are consistent with results of TCA. The correctness and validity of the method is verified.

Background: Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, with an overall prevalence of 4/100,000, accounting for 25–30% of all childhood cancers. With advances in childhood ALL treatment, the cure rate for childhood ALL has exceeded 80% in most countries. However, refractory/relapsed ALL remains a leading cause of treatment failure and subsequent death. Forkhead box O1 (FOXO1) belongs to the forkhead family of transcription factors, but its role in B-cell ALL (B-ALL) has not been determined yet.Procedures: RNA sequencing was applied to an ALL case with induction failure (IF) to identify the possible genetic events. A cytokine-dependent growth assay in Ba/F3 cells was used to test the leukemic transformation capacity of MEIS1–FOXO1. The propidium iodide (PI) staining method was used to evaluate the effect of MEIS1–FOXO1 on cycle distribution. FOXO1 transactivity was examined using a luciferase reporter assay. FOXO1 mRNA expression levels were examined using real-time quantitative PCR among 40 children with B-ALL treated with the CCCG-ALL-2015 protocol. Association analysis was performed to test the correlation of FOXO1 transcription with childhood B-ALL prognosis and relapse in a series of GEO datasets. An MTT assay was performed to test the drug sensitivity.Results: In this ALL case with IF, we identified a novel MEIS1–FOXO1 fusion gene. The transactivity of MEIS1–FOXO1 was significantly lower than that of wild-type FOXO1. MEIS1–FOXO1 potentiated leukemia transformation and promoted Ba/F3 cell cycle S-phase entry. Low FOXO1 transcription levels were found to be strongly associated with unfavorable ALL subtype, minimal residual disease (MRD) positivity, and relapse. Lower FOXO1 expression was associated with prednisone and cyclophosphamide resistance.Conclusions: Low FOXO1 transcription was associated with high-risk stratification and relapse in children with B-ALL, probably due to multi-drug resistance.

A method is proposed to manufacture spiral bevel gear by duplex spread blade method based on 4-axis CNC milling machine. Firstly, the geometry parameters and machine-tool settings are comprehensively considered. To meet with the tooth taper, a new way is raised to select reference point. Then machine-tool settings are calculated that only first-order mesh performance is guaranteed in the reference point. Therefore conjugate tooth surface is modified by a surface represented as second-order polynomial to optimize mesh performance, as a result a target tooth surface is established, and according to the sensitivity matrix the machine-tool settings are corrected. Finally, the proposed method is illustrated by a numerical example to reveal it’s effective and feasible.

In this paper, the method of machining and correcting the two sides of tooth surface of spiral bevel gear pinion with the same cutter head and machine tool is studied. In this method, the cutting procedure and tool path are planned, and the calculation of motion parameters is completed. According to the characteristic that NC machine tool can adjust cutter location in real time, the tooth length and curvature are corrected, and the calculation model of tooth surface deviation is constructed. Five-cutter is used as the target tooth surface to optimize the cutting parameters. An example is introduced to carry out the analysis and gear cutting experiments, which verifies the feasibility of the proposed method.

In order to obtain locally conjugated tooth surface contact, a tooth surface mismatch modification method is proposed based on the fully conjugated characteristics of cycloidal bevel gear. Firstly, according to the principle of fully conjugated, the mathematical model for calculating the cutting parameters of cycloidal bevel gear is established, and the calculating method of the cutting parameters of the fully conjugated tooth surface is deduced. Secondly, the double crowned tooth surface modification method is studied, and the tooth length direction modification is realized by modifying the radius of the cutter blade edge, and the tooth profile direction modification is realized by modifying the shape of cutter blade edge, so that the fully conjugated tooth surfaces meshing with each other are mismatched in the directions of tooth length and tooth profile. On this basis, the mismatch coefficients of tooth surface are calculated by means of polynomial expression of second order. Five coefficients in the mismatch relationship of tooth surface are corrected to modify the tooth surface of pinion again, and the original cutting parameters of pinion are corrected. And then, the required mismatch relationship of tooth surface is obtained. Finally, a pair of cycloidal bevel gear is analyzed in the process of tooth surface mismatch modification. The results of gear cutting experiments are consistent with the simulation results, which verify the effectiveness and feasibility of the proposed tooth surface mismatch modification method.