外文翻译-基于注塑模具钢研磨和抛光工序的自动化表面处理 Shiou FJ/ Chen CH 2003Determination of optimal ball-burnishingparameters for plastic injection molding steel/ Int J Adv Manuf Technol Automated surface finishing of plastic injection mold steel with spherical grinding and ball burnishing processesChao-Chang A/ Chen ? Wen-Tu LiAbstractThis study investigates the possibilities of automated spherical grinding and ball burnishing surface finishing processes in a freeform surface plastic injection mold steel PDS5 on a CNC machining center/ The design and manufacture of a grinding tool holder has been accomplished in this study/ The optimal surface grinding parameters were determined using Taguchis orthogonal array method for plastic injection molding steel PDS5 on a machining center/ The optimal surface grinding parameters for the plastic injection mold steel PDS5 were the combination of an abrasive material of PA Al2O3/ a grinding speed of 18 000 rpm/ a grinding depth of 20 m/ and a feed of 50 mm/min/ The surface roughness Ra of the specimen can be improved from about 1/60 m to 0/35 m by using the optimal parameters for surface grinding/ Surface roughness Ra can be further improved from about 0/343 m to 0/06 m by using the ball burnishing process with the optimal burnishing parameters/ Applying the optimal surface grinding and burnishing parameters sequentially to a fine-milled freeform surface mold insert/ the surface roughness Ra of freeform surface region on the tested part can be improved from about 2/15 m to 0/07 m/Keywords Automated surface finishing ? Ball burnishing process ? Grinding process ? Surface roughness ? Taguchis method1 Introduction Plastics are important engineering materials due to their specific characteristics/ such as corrosion resistance/ resistance to chemicals/ low density/ and ease of manufacture/ and have increasingly replaced metallic components in industrial applications/ Injection molding is one of the important forming processes for plastic products/ The surface finish quality of the plastic injection mold is an essential requirement due to its direct effects on the appearance of the plastic product/ Finishing processes such as grinding/ polishing and lapping are commonly used to improve the surface finish/The mounted grinding tools wheels have been widely used in conventional mold and die finishing industries/ The geometric model of mounted grinding tools for automated surface finishing processes was introduced in/ A finishing process mode of spherical grinding tools for automated surface finishing systems was developed in/ Grinding speed/ depth of cut/ feed rate/ and wheel properties such as abrasive material and abrasive grain size/ are the dominant parameters for the spherical grinding process/ as shown in Fig/ 1/ The optimal spherical grinding parameters for the injection mold steel have not yet been investigated based in the literature In recent years/ some research has been carried out in determining the optimal parameters of the ball burnishing process Fig/ 2/ For instance/ it has been found that plastic deformation on the workpiece surface can be reduced by using a tungsten carbide ball or a roller/ thus improving the surface roughness/ surface hardness/ and fatigue resistance/ The burnishing process is accomplished by machining centers and lathes/ The main burnishing parameters having significant effects on the surface roughness are ball or roller material/ burnishing force/ feed rate/ burnishing speed/ lubrication/ and number of burnishing passes/ among others/ The optimal surface burnishing parameters for the plastic injection mold steel PDS5 were a combination of grease lubricant/ the tungsten carbide ball/ a burnishing speed of 200 mm/min/ a burnishing force of 300 N/ and a feed of 40 m/ The depth of penetration of the burnished surface using the optimal ball burnishing parameters was about 2/5 microns/ The improvement of the surface roughness through burnishing process generally ranged between 40% and 90%/ Fig/ 2/ Schematic diagram of the ball-burnishing process The aim of this study was to develop spherical grinding and ball burnishing surface finish processes of a freeform surface plastic injection mold on a machining center/ The flowchart of automated surface finish using spherical grinding and ball burnishing processes is shown in Fig/ 3/ We began by designing and manufacturing the spherical grinding tool and its alignment device for use on a machining center/ The optimal surface spherical grinding parameters were determined by utilizing a Taguchis orthogonal array method/ Four factors and three corresponding levels were then chosen for the Taguchis L18 matrix experiment/ The optimal mounted spherical grinding parameters for surface grinding were then applied to the surface finish of a freeform surface carrier/ To improve the surface roughness/ the ground surface was further burnished/ using the optimal ball burnishing parameters/ Fig/ 3/ Flow chart of automated surface finish using spherical grinding and ball burnishing processes2 Design of the spherical grinding tool and its alignment device To carry out the possible spherical grinding process of a freeform surface/ the center of the ball grinder should coincide with the z-axis of the machining center/ The mounted spherical grinding tool and its adjustment device was designed/ as shown in Fig/ 4/ The electric grinder was mounted in a tool holder with two adjustable pivot screws/ The center of the grinder ball was well aligned with the help of the conic groove of the alignment components/ Having aligned the grinder ball/ two adjustable pivot screws were tightened/ after which/ the alignment components could be removed/ The deviation between the center coordinates of the ball grinder and that of the shank was about 5 m/ which was measured by a CNC coordinate measuring machine/ The force induced by the vibration of the machine bed is absorbed by a helical spring/ The manufactured spherical grinding tool and ball-burnishing tool were mounted/ as shown in Fig/ 5/ The spindle was locked for both the spherical grinding process and the ball burnishing process by a spindle-locking mechanism/ Fig/4/ Schematic illustration of the spherical grinding tool and its adjustment device Fig/5/ a Photo of the spherical grinding tool b Photo of the ball burnishing tool 3 Planning of the matrix experiment3/1 Configuration of Taguchis orthogonal array The effects of several parameters can be determined efficiently by conducting matrix experiments using Taguchis orthogonal array/ To match the aforementioned spherical grinding parameters/ the abrasive material of the grinder ball with the diameter of 10 mm/ the feed rate/ the depth of grinding/ and the revolution of the electric grinder were selected as the four experimental factors parameters and designated as factor A to D see Table 1 in this research/ Three levels settings for each factor were configured to cover the range of interest/ and were identified by the digits 1/ 2/ and 3/ Three types of abrasive materials/ namely silicon carbide SiC/ white aluminum oxide Al2O3/ WA/ and pink aluminum oxide Al2O3/ PA/ were selected and studied/ Three numerical values of each factor were determined based on the pre-study results/ The L18 orthogonal array was selected to conduct the matrix experiment for four 3-level factors of the spherical grinding process/Table1/ The experimental factors and their levels3/2 Definition of the data analysis Engineering design problems can be divided into smaller-the better types/ nominal-the-best types/ larger-the-better types/ signed-target types/ among others 8/ The signal-to-noise S/N ratio is used as the objective function for optimizing a product or process design/ The surface roughness value of the ground surface via an adequate combination of grinding parameters should be smaller than that of the original surface/ Consequently/ the spherical grinding process is an example of a smaller-the-better type problem/ The S/N ratio/ / is defined by the following equation/ ?10 log10mean square quality characteristic ?10 log10 where/ yi / observations of the quality characteristic under different noise conditions n/ number of experiment After the S/N ratio from the experimental data of each L18 orthogonal array is calculated/ the main effect of each factor was determined by using an analysis of variance ANOVA technique and an F-ratio test/ The optimization strategy of the smaller-the better problem is to imize / as defined by Eq/ 1/ Levels that imize will be selected for the factors that have a significant effect on / The optimal conditions for spherical grinding can then be determined/ 4 Experimental work and results The material used in this study was PDS5 tool steel equivalent to AISI P20/ which is commonly used for the molds of large plastic injection products in the field of automobile components and domestic appliances/ The hardness of this material is about HRC33 HS46/ One specific advantage of this material is that after machining/ the mold can be directly used for further finishing processes without heat treatment due to its special pre-treatment/ The specimens were designed and manufactured so that they could be mounted on a dynamometer to measure the reaction force/ The PDS5 specimen was roughly machined and then mounted on the dynamometer to carry out the fine milling on a three-axis machining center made by Yang-Iron Company type MV-3A/ equipped with a FUNUC Company NC-controller type 0M/ The pre-machined surface roughness was measured/ using Hommelwerke T4000 equipment/ to be about 1/6 m/ Figure 6 shows the experimental set-up of the spherical grinding process/ A MP10 touch-trigger probe made by the Renishaw Company was also integrated with the machining center tool magazine to measure and determine the coordinated origin of the specimen to be ground/ The NC codes needed for the ball-burnishing path were generated by PowerMILL CAM software/ These codes can be transmitted to the CNC controller of the machining center via RS232 serial interface/ Fig/6/ Experimental set-up to determine the optimal spherical grinding parameters Table 2 summarizes the measured ground surface roughness alue Ra and the calculated S/N ratio of each L18 orthogonal array sing Eq/ 1/ after having executed the 18 matrix experiments/ The average S/N ratio for each level of the four actors is shown graphically in Fig/ 7/Table2/ Ground surface roughness of PDS5 specimenExp/Inner array control factorsMeasured surface roughness value RaResponsenoABCDS/NdBMean111110/350/350/359/1190/350212220/370/360/388/6340/370313330/410/440/407/5970/417421230/630/650/643/8760/640522310/730/770/782/3800/760623120/450/420/397/5300/420731320/340/310/329/8010/323832130/270/250/2811/4710/267933210/320/320/329/8970/3201011220/350/390/408/3900/3801112330/410/500/436/9680/4471213110/400/390/427/8830/4031321130/330/340/319/7120/3271422210/480/500/476/3120/4831523320/570/610/534/8680/5701631310/590/550/545/0300/5601732120/360/360/358/9540/3571833230/570/530/535/2930/543Fig/7/ Plots of control factor effects The goal in the spherical grinding process is to minimize the surface roughness value of the ground specimen by determining the optimal level of each factor/ Since ?log is a monotone decreasing function/ we should imize the S/N ratio/ Consequently/ we can determine the optimal level for each factor as being the level that has the highest value of / Therefore/ based on the matrix experiment/ the optimal abrasive material was pink aluminum oxide/ the optimal feed was 50 mm/min/ the optimal depth of grinding was 20 m/ and the optimal revolution was 18 000 rpm/ as shown in Table 3/ The optimal parameters for surface spherical grinding obtained from the Taguchis matrix experiments were applied to the surface finish of the freeform surface mold insert to evaluate the surface roughness improvement/ A perfume bottle was selected as the tested carrier/ The CNC machining of the mold insert for the tested object was simulated with Power MILL CAM software/ After fine milling/ the mold insert was further ground with the optimal spherical grinding parameters obtained from the Taguchis matrix experiment/ Shortly afterwards/ the ground surface was burnished with the optimal ball burnishing parameters to further improve the surface roughness of the tested object see Fig/ 8/ The surface roughness of the mold insert was measured with Hommelwerke T4000 equipment/ The average surface roughness value Ra on a fine-milled surface of the mold insert was 2/15 m on average/ that on the ground surface was 0/45 m on average/ and that on burnished surface was 0/07 m on average/ The surface roughness improvement of the tested object on ground surface was about 2/15?0/45/2/15 79/1%/ and that on the burnished surface was about 2/15?0/07/2/15 96/7%/Fig/8/ Fine-milled/ ground and burnished mold insert of a perfume bottle5 Conclusion In this work/ the optimal parameters of automated spherical grinding and ball-burnishing surface finishing processes in a freeform surface plastic injection mold were developed successfully on a machining center/ The mounted spherical grinding tool and its alignment components was designed and manufactured/ The optimal spherical grinding parameters for surface grinding were determined by conducting a Taguchi L18 matrix experiments/ The optimal spherical grinding parameters for the plastic injection mold steel PDS5 were the combination of the abrasive material of pink aluminum oxide Al2O3/ PA/ a feed of 50 mm/min/ a depth of grinding 20 m/ and a revolution of 18 000 rpm/ The surface roughness Ra of the specimen can be improved from about 1/6 m to 0/35 m by using the optimal spherical grinding conditions for surface grinding/ By applying the optimal surface grinding and burnishing parameters to the surface finish of the freeform surface mold insert/ the surface roughness improvements were measured to be ground surface was about 79/1% in terms of ground surfaces/ and about 96/7% in terms of burnished surfacesAcknowledgement The authors are grateful to the National Science Council of the Republic of China for supporting this research with grant NSC 89-2212-E-011-059/ References1/ Wang KK 1980 System approach to injection molding process/ Polym-Plast Technol Eng 141/75?93/2/ Shelesh-Nezhad K/ Siores E 1997 Intelligent system for plastic injection molding process design/ J Mater Process Technol 631?3/458?462/3/ Aluru R/ Keefe M/ Advani S 2001 Simulation of injection molding into rapid-prototyped molds/ Rapid Prototyping J 71/42?51/4/ Shen SF 1984 Simulation of polymeric flows in the injection molding process/ Int J Numer Methods Fluids 42/171?184/5/ Agassant JF/ Alles H/ Philipon S/ Vincent M 1988 Experimental and theoretical study of the injection molding of thermoplastic materials/ Polym Eng Sci 287/460?468/6/ Chiang HH/ Hieber CA/ Wang KK 1991 A unified simulation of the filling and post-filling stages in injection molding/ Part I/ formulation/ Polym Eng Sci 312/116?124/7/ Zhou H/ Li D 2001 A numerical simulation of the filling stage in injection molding based on a surface model/ Adv Polym Technol 202/125?131/8/ Himasekhar K/ Lottey J/ Wang KK 1992 CAE of mold cooling in injection molding using a three-dimensional numerical simulation/ J EngInd Trans ASME 1142/213?221/9/ Tang LQ/ Pochiraju K/ Chassapis C/ Manoochehri S 1998 Computeraided optimization approach for the design of injection mold cooling systems/ J Mech Des/ Trans ASME 1202/165?174/10/ Rizzo FJ/ Shippy DJ 1977 An advanced boundary integral equation method for three-dimensional thermoelasticity/ Int J Numer Methods Eng 11/1753?1768/11/ Hartmann F 1980 Computing the C-matrix in non-smooth boundary points/ In/ New developments in boundary element methods/ CML Publications/ Southampton/ pp 367?379/12/ Chen X
免责声明：
1. 《外文翻译--基于注塑模具钢研磨和抛光工序的自动化表面处理》内容来源于互联网，版权归原著者或相关公司所有。
2. 若《86561825文库网》收录的文本内容侵犯了您的权益或隐私，请立即通知我们删除。
