Investigation of MS and Anti-segregation Process HSS Flat Broaching Tools

An investigation has been carried out to compare th e cutting performance and tool life evaluation of high speed steel broach samp les. The comparison has been done between conventional M2 and Anti-Segregation Process (ASP) ASP53 and ASP30 high speed steel broach samples. The ASP53 was a development material. The cutting performance was evaluated by measuring the c utting forces and calculating the specific cutting energy, an indicator of cutti ng performance. As the roughness of the machined surface is an important criter ion in the evaluation of performance of a tool, the surface roughness of the workpiece was studied as a function of undeformed chip thickness. The workpiec e material was 150M36 alloy steel used in manufacture of automobile engines. Th e performance tests were conducted at two cutting speeds, which were 0 7 m/min and 10.5 m/min respectively. This allowed a better understanding of the effect of cutting speed on tool performance. The wear tests were performed at a cuttin g speed on 10.5 m/min. The cutting edges of ASP broach samples were finer compared to that of M2. Ther e was no practical difference in the cutting forces and the specific cutting ene rgy while cutting with MS, ASP30 and ASP53 broach samples. The ASP30 and ASP53 tools have a better surface roughness on the machined surface than that of M2 at both cutting speeds. The ASP30 gave 2.25 times the life and an improved surfac e finish compared to M2 steel. The ASP53 gave 1.3 times the life of M2 steel. These results should prove useful to the tool designer and manufacturing enginee r.

Assessment of water-based cutting fluids with green additives in broaching

In order to improve the cutting performance in broaching,the lubrication and cleaning effects offered by water-based cutting fluids with green additives need to be studied from the viewpoint of green manufacturing.Therefore,water-based solutions with castor oil,surfactant(linear alkylbenzene sulfonate,LAS),and nanographite were prepared by ultrasonic agitation and sprayed into the zone of broaching via atomization.The performances of the cutting fluids,in terms of the viscosity,specific heat,wetting angle,and droplet size,were evaluated to discuss their effects on the broaching load.Among the fluids,the addition of LAS into oil-in-water(WO-S),where its cutting fluid with 10 wt.%castor oil and 1.5 wt.%surfactant,exhibited the lowest broaching force.With regard to the lubricating and cleaning mechanisms,WO-S has good wettability and permeability,and hence,can lubricate the cutting edge of the tool to decrease the cutting load,cool the cutting edge to keep it sturdy,and clean the surface of the cutting edge to keep it sharp.The results reveal that the simultaneous addition of castor oil and LAS had remarkable effects on the lubrication and cleaning,and resulted in a broaching load reduction of more than 10%compared to commercial cutting fluids.However,the addition of nanographite could not improve the lubrication owing to its agglomeration.

Penetration and lubrication evaluation of vegetable oil with nanographite particles for broaching process

With increasing environmental concerns,the substitution of mineral oil-based cutting fluid has become an urgent issue.Using vegetable soybean oil as base fluid,nanofluid cutting fluids(NFCFs)were prepared by adding different weight concentrations of nanographite particles(NGPs),and their penetration and lubrication performances were studied.A novel simulated tool-chip slit with micrometersized geometry was manufactured to evaluate and quantify the penetration rate of the NFCFs by image analysis approach.Moreover,a large number of comparative experiments on the closed-type broaching machine were carried out to compare the performance of the proposed NFCFs and a commercial cutting fluid in terms of cutting force,workpiece surface roughness,and metal chip.It is found that there is an optimal NGP concentration in NFCF for practical cutting applications.When the concentration of NGP is 0.4 wt%,the broaching process lubrication exhibits an ideal mixed lubricate state,resulting in minimal friction resistance,and thus,both the cutting force and chip curling angle reach their corresponding best values.Moreover,the proposed NGP-based vegetable-oil cutting fluid exhibits excellent environmentfriendliness and low-cost consumption in the minimal quantity lubrication(MQL)method;this demonstrates its potential for replacing the traditional broaching cutting fluid.

Correction of Wave Surge Forces to Improve Surf-Riding/Broaching Vulnerability Criterion Check Accuracy

Surf-riding/broaching is one of the five stability failure modes to be included into the International Maritime Organization(IMO) second generation intact stability criteria(which are risk-based stability criteria)that can ensure the safety of ships in actual seaways more effectively. This study focuses on the influence of wave surge force prediction accuracy on surf-riding/broaching vulnerability criterion check result. Firstly, it is demonstrated that the wave surge force prediction method adopted in the current vulnerability criterion check procedure is not accurate and may lead to wrong conclusions. The experimental data from captive model test and the numerical result based on 3D panel method both indicate that the diffraction effect must be considered to correctly predict the wave surge forces. Besides, sophisticated methods are not suitable for Level 2 vulnerability criterion check due to their complexity. Therefore, an empirical formula for wave surge force correction based on sample ship calculation results is proposed. The proposed empirical correction formula can effectively improve the vulnerability criterion check accuracy and thus contribute to the design and safety of the ships which are vulnerable to this stability failure mode.

The influence of wave surge force on surf-riding/broaching vulnerability criteria check

This study focuses on the influence of the wave surge force on the assessments of the surf-riding/broaching vulnerability criteria according to the new proposal of the IMO Second Generation Intact Stability Criteria. A code is developed for the criteria check and the sample ship calculations show that the accuracy of the wave surge force estimation has a significant influence on the assessment result. For further investigation, the wave surge force measurement through a captive model test is made for a purse seiner to validate the numerical model, the effects of the wave steepness and the ship forward speed on the wave surge force responses are also discussed. It is demonstrated that the diffraction effect is important for the correct estimation of the wave surge force. Therefore, it is recommended to include this effect in the assessment procedure.

反掩体巡航导弹战斗部及引信简介

阐述了欧美国家在增强巡航导弹打击能力方面所做的努力,介绍了Mephis-to、BROACH和AUP三种新型导弹的工作机理。要想增强巡航导弹打击能力,主要应对战斗部进行改进,并同时提高引信的技术水平。