机械外文翻译---基于注塑模具钢研磨和抛光工序的自动化表面处理-模具设计

1、zzzzzzz大学毕业设计论文外文文献 学 院 xxxxxxxx 专业班级 xxxxxx 学生姓名 xxxxx 指导教师 xxxxxx Automated surface finishing of plastic injection mold steel with spherical grinding and ball burnishing processesAbstractThis study investigates the possibilities of automated spherical grinding and ball burnishing surface finishing

2、 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

3、 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 sp

4、ecimen 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 bu

5、rnishing 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

6、method1 IntroductionPlastics 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

7、 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

8、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 automate

9、d 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 injecti

10、on mold steel have not yet been investigated based in the literature.Fig.1. Schematic diagram of the spherical grinding processIn 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 plast

11、ic 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 significa

12、nt 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

13、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 generall

14、y ranged between 40% and 90%.Fig. 2. Schematic diagram of the ball-burnishing processThe 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 usin

15、g 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 arra

16、y 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 su

17、rface 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 deviceTo carry out the possible spherical grinding process of a fre

18、eform 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

19、 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

20、 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

21、 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 deviceFig.5. (a) Photo of the spherical grinding tool (b) Photo of the ball burnishing tool3 Planning of the matrix expe

22、riment3.1 Configuration of Taguchis orthogonal arrayThe 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 diamete

23、r 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 inte

24、rest, 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

25、. 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 analysisEngineering design problems can be divided into smaller-the better types, nominal-th

26、e-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 sma

27、ller 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 log10(mean square quality characteristic) =10 log10where:yi : observations of the quality characteristic

28、 under different noise conditions n: number of experimentAfter 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 s

29、maller-the better problem is to maximize , as defined by Eq. 1. Levels that maximize 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 resultsThe material used in this study was PDS5 tool

30、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 b

31、e 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 dynamomet

32、er 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-

33、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 P

34、owerMILL 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 parametersTable 2 summarizes the measured ground surface roughness alue Ra and the calculated S/N rati

35、o 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 factors)Measured surface roughness value (Ra)Re

36、sponsenoABCDS/N(dB)Mean111112122231333421235223162312731328321393321101122111233121311132113142221152332163131173212183323Fig.7. Plots of control factor effectsThe goal in the spherical grinding process is to minimize the surface roughness value of the ground specimen by determining the optimal leve

37、l of each factor. Since log is a monotone decreasing function, we should maximize 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 alumi

38、num 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 sur

39、face 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 spherica

40、l 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

41、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 grou

42、nd surface was about (2.150.45)/2.15 = 79.1%, and that on the burnished surface was about (2.150.07)/2.15 = 96.7%.Fig.8. Fine-milled, ground and burnished mold insert of a perfume bottle5 ConclusionIn this work, the optimal parameters of automated spherical grinding and ball-burnishing surface finis

43、hing 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 conductin

44、g 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 roughne

45、ss 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 w

46、ere measured to be ground surface was about 79.1% in terms of ground surfaces, and about 96.7% in terms of burnished surfaces. Acknowledgement 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.基于注塑模具钢研磨和抛光工

47、序的自动化外表处理摘要本文研究了注塑模具钢自动研磨与球面抛光加工工序的可能性，这种注塑模具钢PDS5的塑性曲面是在数控加工中心完成的。这项研究已经完成了磨削刀架的设计与制造。 最正确外表研磨参数是在钢铁PDS5 的加工中心测定的。对于PDS5注塑模具钢的最正确球面研磨参数是以下一系列的组合：研磨材料的磨料为粉红氧化铝，进给量500毫米/分钟，磨削深度20微米，磨削转速为18000RPM。用优化的参数进行外表研磨，外表粗糙度Ra值。 用球抛光工艺和参数优化抛光，可以进一步改善外表粗糙度Ra值。在模具内部曲面的测试局部，用最正确参数的外表研磨、抛光，。关键词: 自动化外表处理 抛光 磨削加工 外表

48、粗糙度 田口方法 一、引言塑胶工程材料由于其重要特点,如耐化学腐蚀性、低密度、易于制造,并已日渐取代金属部件在工业中广泛应用。 注塑成型对于塑料制品是一个重要工艺。注塑模具的外表质量是设计的本质要求,因为它直接影响了塑胶产品的外观和性能。 加工工艺如球面研磨、抛光常用于改善外表光洁度。研磨工具(轮子)的安装已广泛用于传统模具的制造产业。自动化外表研磨加工工具的几何模型将介绍。自动化外表处理的球磨研磨工具将得到示范和开发。 磨削速度, 磨削深度，进给速率和砂轮尺寸、研磨材料特性如磨料粒度大小是球形研磨工艺中主要的参数，如图1球面研磨过程示意图所示。注塑模具钢的球面研磨最优化参数目前尚未在文献得到

49、确切的依据。 步距研磨高度球磨研磨进给速度工作台图1 球面研磨过程示意图进给研磨球工作台研磨深度研磨外表近年来 ，已经进行了一些研究，确定了球面抛光工艺的最优参数(图2) 球面抛光过程示意图。 比方，人们发现, 用碳化钨球滚压的方法可以使工件外表的塑性变形减少,从而改善外表粗糙度、外表硬度、抗疲劳强度。 抛光的工艺的过程是由加工中心和车床共同完成的。对外表粗糙度有重大影响的抛光工艺主要参数，主要是球或滚子材料，抛光力， 进给速率,抛光速度,润滑、抛光率及其他因素等。注塑模具钢PDS5的外表抛光的参数优化，分别结合了油脂润滑剂，碳化钨球,抛光速度200毫米/分钟,抛光力300牛，40微米的进给量

50、。采用最正确参数进行外表研磨和球面抛光的深度。 通过抛光工艺，外表粗糙度可以改善大致为40至90。 图2 球面抛光过程示意图此工程研究的目的是，开展注塑模具钢的球形研磨和球面抛光工序，这种注塑模具钢的曲面实在加工中心完成的。外表光洁度的球研磨与球抛光的自动化流程工序，如图3所示。 我们开始自行设计和制造的球面研磨工具及加工中心的对刀装置。利用田口正交法，确定了外表球研磨最正确参数。选择为田口L18型矩阵实验相应的四个因素和三个层次。 用最正确参数进行外表球研磨那么适用于一个曲面外表光洁度要求较高的注塑模具。 为了改善外表粗糙, 利用最正确球面抛光工艺参数，再进行对表层打磨。PDS试样的设计与制

51、造选择最正确矩阵实验因子确定最正确参数实施实验分析并确定最正确因子进行外表抛光应用最正确参数加工曲面测量试样的外表粗糙度球研磨和抛光装置的设计与制造图3自动球面研磨与抛光工序的流程图二、球研磨的设计和对准装置实施过程中可能出现的曲面的球研磨,研磨球的中心应和加工中心的Z轴相一致。 球面研磨工具的安装及调整装置的设计，如图4球面研磨工具及其调整装置所示。电动磨床展开了两个具有可调支撑螺丝的刀架。磨床中心正好与具有辅助作用的圆锥槽线配合。 拥有磨床的球接轨,当两个可调支撑螺丝被收紧时，其后的对准部件就可以撤除。研磨球中心坐标偏差约为5微米, 这是衡量一个数控坐标测量机性能的重要标准。 机床的机械振

52、动力是被螺旋弹簧所吸收。球形研磨球和抛光工具的安装，如图5a. 球面研磨工具的图片. b.球抛光工具的图片所示。为使球面磨削加工和抛光加工的进行，主轴通过球锁机制而被锁定。 模柄弹簧工具可调支撑紧固螺钉磨球自动研磨磨球组件图4 球面研磨工具及其调整装置图5 a. 球面研磨工具的图片. b.球抛光工具的图片三、矩阵实验的规划利用矩阵实验田口正交法，可以确定参数的有影响程度。 为了配合上述球面研磨参数，该材料磨料的研磨球(直径10毫米),进给速率，研磨深度,在次研究中电气磨床被假定为四个因素，指定为从A到D见表1实验因素和水平。三个层次的因素涵盖了不同的范围特征,并用了数字1、2、3标明。挑选三类磨料,即碳化硅,白色氧化铝,粉红氧化铝来研究. 这三个数值的大小取决于每个因素实验结果。选定L18型正交矩阵进行实验，进而研究四三级因素的球形研磨过程。表1实验因素和水平因素水平123A.碳化硅白色氧化铝粉红氧化铝B.50100200C.研磨深度m205080D.1200018000240003.2数据分析的界定 工程设计问题,可以分为较小而好的类型,象征性最好类型,大而好类型，目标取向类型等。 信噪比(S/N)的比值，常作为目标函数来优化产品或者工艺设计。 被加工面的外表粗糙度值经过适当地组合磨削参数，应小于原来的未加工外表