袋式包装机横封切杆机构的设计与特性分析

横封切机构是袋式等包装机的重要执行机构之一。目前横封切机构采用杆机构比较多,设计模式主要是依靠设计人员的经验和模仿为主,不能全面反映横封切杆机构的动态工作过程,故在实际应用中振动和冲击比较大。因此,利用ANSYS软件模拟其运动、受力、振动情况,定量分析机构的运动学和动力学特性,可使横封切机构避免刚性冲击和减少柔性冲击。

女子高尔夫球运动员冯珊珊与朴仁妃切推杆技术对比分析

目的:鉴于世界优秀女子高尔夫球运动员冯珊珊(中国)与朴仁妃(韩国)参加东京奥运会的概率较大,通过比较两人的技术特征做到知己知彼,为冯珊珊开展专项技术训练、进行奥运备战提供助力。方法:运用视频分析法、数理统计法对两人的切推杆技术进行对比分析。结果:①朴仁妃沙坑救球率整体高于冯珊珊,每洞、每轮平均推杆数朴仁妃整体表现较优于冯珊珊,但冯珊珊标ON率曲线图呈现“一”字形,稳定性更好,到2018年两人沙坑救球率已相近。②每洞与每轮平均推杆数变化趋势相似,朴仁妃表现好于冯珊珊,但冯珊珊有趋于向好的走势。③两人切杆技术均通过控制上杆幅度达到不同距离,但冯姗姗切杆节奏更快,朴仁妃切杆节奏表现变化更大。④朴仁妃的推杆技术具有“慢后快前”的特征,冯珊珊则表现为“后前快慢变化不明显”的特征。建议:冯珊珊可尝试增加髋部旋转角度完善切杆打法,适应不同难度的切杆击球;推杆方面可挖掘潜力和优化空间较大,加强推送距离和方向的控制能力,提高动作的整体性和稳定性。

新型高效高精度切槽刀杆结构及应用

介绍一种新颖、高效、高精度切槽刀杆的结构、原理、调整及应用。它可以大大提高生产线上箱体孔切槽加工的效率 ,而且具有精度高、寿命长等特点。

新型切槽刀杆结构及应用

介绍了一种高效、高精度切槽刀杆的结构、原理、调整及应用,采用该种刀杆可以大大提高生产线上箱体孔切槽加工的效率,而且具有精度高、寿命长等特点。

孔内环切槽刀杆的两种形式

在机械加工过程中，箱体或壳体的零件上，经常会出现如图1与图2所示孔内环槽形状的结构。传统的加工工艺方法，大多采用普通的钻床或镗床进行加工。但对于一些精度要求高，且与所在孔同轴的环形内密封槽、油槽、内挡圈槽(见图1与图2)，就必须采用专用的、具有径向进给量的刀杆才能完成。为此，针对零件的不同形式与要求，

内孔切槽刀杆

在加工箱体或壳体的零件时,经常会出现如图1与图2所示内孔环形槽的结构.按传统的加工工艺,大多采用普通钻床或镗床进行加工.

瓦尔特精密内冷整体式内孔切槽刀杆G1221-P

瓦尔特首次向市场推出带选装第二个冷却孔的整体式内孔切槽刀杆G1221-P。通过上压板和可封闭的轴向冷却孔进行精密内冷，使得铁屑顺利地从盲孔冲出。在加工通孔时，精密内冷可以提高切槽的寿命和效率。通过。形密封圈确保刀杆和刀座之间的接口无泄漏、无压力损失。保证必要的冷却液压力。

平压模切机构及其运动协调性的分析研究

本文分析了模切压力肘杆机构的结构特点与运动特性,讨论了机构的增力效应及影响因素,在忽略了次要因素的简化模型上,分析推导了双列链条间歇运动的动静比、模版行程、杆件尺寸之间的解析关系,为机构设计提供了理论依据。

Dynamic fracture of Ti-6Al-4V alloy in Taylor impact test

The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.

单自由度四足机器人腿部行走机构分析

本文介绍了由切比雪夫四杆机构和平行四边形缩放机构组成,衍化得到的一种单自由度四足机器人的腿部行走机构。首先建立平面坐标系并利用解析法,根据腿部机构简图建立相应的数学模型,得出该机构的运动学方程。其次,在机构分析SAM环境下对该腿部机构进行运动仿真分析,得到足端轨迹图,并改变腿部机构中变量大小观察足端轨迹的变化。最终确定了方案的可行性以及机构设计的合理性。该机构提出了一种成本低,节约能源的,易于实现的单自由度四足机器人的腿部机构。

Evaluation of dynamic performance and ballistic behavior of Ti-5Al-5Mo-5V-3Cr-1Zr alloy

Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were determined by a split Hopkinson pressure bar （SHPB） test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.

Cloning of Endo-β-Glucanase Ⅲ and Expression in Eerevisiae Fermentum

Objective The aim was to construct bioengineering strains that could degrade the cellulosic solid waste. Method The cDNA of endo-β-glucanase III of Trichoderma vi ride AS313711 was cloned by RT-PCR method. After sequenced, this gene was constructed to expression vector pESP-2, and then the plasmid was transformed into competent cell of cerevisiae fermentum by electric shock, the transformant was then obtained. The enzyme activity of this transformant at the different temperatures and pH was measured by DNS method. Result The length of ORF of EG III was 1 257 bp, encoding 418 amino acids, while the deduced molecular weight was 44.1 × 103 kD. Conclusion The enzyme activity of EG III was the highest when it was at PH 4.9 and tempeture was of 60℃. Then the corresponding enzyme activity was about 100%.

A systematic review and meta-analysis of the Chinese literature for the treatment of achalasia

AIM: To evaluate the effect of different approaches in the treatment of achalasia in China. METHODS: We performed a systematic review and meta-analysis of Chinese literature by searching the Chinese Biomedical Database and Chinese scientific Journals database (up to March 2008). All cohort studies (controlled or uncontrolled) in which the patients were observed for more than a year were reviewed in detail. Dichotomous outcomes were reported as relative risks (RR) with 95% confidence interval (CI) for controlled trials. The efficacy in uncontrolled trials was assessed by a pooled estimate of response rate with individual studies weighted in proportion to the sample size. RESULTS: Seven controlled trials compared the effect of botulinum toxin injection (BoTx) with pneumatic dilation (PD). PD was superior to BoTx [65.2% vs 45.3%; RR 1.47 (95% CI 1.23-1.77), P < 0.0001], and had a lower clinical relapse rate (BoTx 30.2% vs PD 10%, RR 0.32 (0.16-0.65), P = 0.001). Heller myotomy (HM) had superior remission rate compared to PD [HM 94.0% vs PD 64.1%, RR 1.48 (1.15-1.99), P = 0.002]. In uncontrolled trials, the effectiveness of PD was 86.6% (23.9%) vs 94.8% (10.6%) for HM. The main complications of PD were perforation and gastroesophageal reflux disease. CONCLUSION: HM is the most effective long-term treatment for patients with achalasia in China. In the future, controlled clinical trials on the treatment of achalasia should focus on comparing laparoscopic myotomy with or without antireflux procedure,including different partial and total fundoplication techniques.

A new analytical solution for calculation the displacement and shear stress of fully grouted rock bolts and numerical verifications

In presence of difficult conditions in coal mining roadways, an adequate stabilization of the excavation boundary is required to ensure a safe progress of the construction. The stabilization of the roadways can be improved by fully grouted rock bolt, offering properties optimal to the purpose and versatility in use. Investigations of load transfer between the bolt and grout indicate that the bolt profile shape and spacing play an important role in improving the shear strength between the bolt and the surrounding strata. This study proposes a new analytical solution for calculation displacement and shear stress in a fully encapsulated rock bolt in jointed rocks. The main characteristics of the analytical solution consider the bolt profile and jump plane under pull test conditions. The performance of the proposed analytical solution, for three types of different bolt profile configurations, is validated by ANSYS software. The results show there is a good agreement between analytical and numerical methods. Studies indicate that the rate of displacement and shear stress from the bolt to the rock exponentially decayed. This exponential reduction in displacement and shear stress are dependent on the bolt characteristics such as: rib height, rib spacing, rib width and grout thickness, material and joint properties.

Fatigue damage evaluation by metal magnetic memory testing

Tension-compression fatigue test was performed on 0.45% C steel specimens.Normal and tangential components of magnetic memory testing signals,Hp(y) and Hp(x) signals,with their characteristics,K of Hp(y) and Hp(x)M of Hp(x),throughout the fatigue process were presented and analyzed.Abnormal peaks of Hp(y) and peak of Hp(x) reversed after loading; Hp(y) curves rotated clockwise and Hp(x) curves elevated significantly with the increase of fatigue cycle number at the first a few fatigue cycles,both Hp(y) and Hp(x) curves were stable after that,the amplitude of abnormal peaks of Hp(y) and peak value of Hp(x) increased more quickly after fatigue crack initiation.Abnormal peaks of Hp(y) and peak of Hp(x) at the notch reversed again after failure.The characteristics were found to exhibit consistent tendency in the whole fatigue life and behave differently in different stages of fatigue.In initial and crack developing stages,the characteristics increased significantly due to dislocations increase and crack propagation,respectively.In stable stage,the characteristics remained constant as a result of dislocation blocking,K value ranged from 20 to 30 A/(m·mm)-1,and Hp(x)M ranged from 270 to 300 A/m under the test parameters in this work.After failure,both abnormal peaks of Hp(y) and peak of Hp(x) reversed,K value was 133 A/(m·mm)-1 and Hp(x)M was-640 A/m.The results indicate that the characteristics of Hp(y) and Hp(x) signals were related to the accumulation of fatigue,so it is feasible and applicable to monitor fatigue damage of ferromagnetic components using metal magnetic memory testing(MMMT).

Relationship between loading angle and displacing angle in steel bolt shearing

When subjected to shear loading condition,a steel rock bolt will become bent in the field close to the loading point in situ.The bolt is deformed as the joint displacement increases,which can mobilize a normal load and a shear load on the bolt accordingly.In this work,the relationship analysis between the displacing angle and loading angle is carried out.By considering elastic andplastic states of rock bolt during shearing,the rotation of bolt extremity can be calculated analytically.Thus,the loading angle isobtained from displacing angle.The verification of analytical results and laboratory results from reference research implies that theanalytical method is correct and working.In terms of in-situ condition,the direction of the load acting on steel bolt can be predictedwell according to the direction of the deformed rock bolt with respect to original bolt axis.

Delayed gastric emptying is associated with pylorus-preserving but not classical Whipple pancreaticoduodenectomy:A review of the literature and critical reappraisal of the implicated pathomechanism

Pylorus-preserving pancreaticoduodenectomy （PPPD） is nowadays considered the treatment of choice for periampullary tumors, namely carcinoma of the head, neck, or uncinate process of the pancreas, the ampulla of Vater, distal common bile duct or carcinoma of the peri-Vaterian duodenum. Delayed gastric emptying （DGE） comprises one of the most troublesome complications of this procedure. A search of the literature using Pubmed/IVledline was performed to identify clinical trials examining the incidence rate of DGE following standard Whipple pancreaticoduodenectomy （PD） vs PPPD. Additionally we performed a thorough in-depth analysis of the implicated pathomechanism underlying the occurrence of DGE after PPPD. In contrast to early studies, the majority of recently performed clinical trials demonstrated no significant association between the occurrence of DGE with either PD or PPPD. PD and PPPD procedures are equally effective operations regarding the postoperative occurrence of DGE. Further randomized trials are required to investigate the efficacy of a recently reported （but not yet tested in largescale studies） modification, that is, PPPD with antecolic duodenojejunostomy.

Characterization of tensile and shear loading on indented PC-strand cable bolts

The tensile and shear strength of intrinsic bolting support systems has always been a major concern of designers. A comprehensive laboratory testing program was designed to evaluate the tensile and shear strength of individual wires and completely wound PC-strand cables. PC-strand cables with smooth wires and the recent anchorage enhancement innovation of indentation were evaluated and compared. The testing protocol detailed in ISO Standard 15630 utilizes a mandrel system that was investigated at 3different diameters which alters the wire to mandrel ratio from 2:1 to 9:1. The results demonstrate that the difference between smooth and indented wires is statistically insignificant when larger diameter mandrels are used,and that indentation does not adversely affect strand properties and performance.Insight into the shearing mechanism and evaluation techniques are discussed with the introduction of triaxial loading to describe the PC-strand tensile and shearing mechanisms. Another important result indicates that the shear strength of PC-strand cable bolting systems has a greater shear strength value than traditional steel bar bolting systems.

Microscope产品线

知名的刀具专家瓦格斯公司，怀着对Groovex产品线的全情投入，推出了可应用于全行业加工的切槽刀杆和刀片产品系列。在Groovex家族中Microscope产品线为小孔切槽、镗孔和螺纹加工（最小至1mm）提供了可转位硬质合金刀片。