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黃河科技學(xué)院畢業(yè)(文獻(xiàn)翻譯) 第 13 頁(yè) Based on the injection mold steel grinding and polishing processes automated surface treatmentChao-Chang A. Chen Wen-Tu LiAbstract:This 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.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 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 forthe injection 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 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 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 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 deviceTo 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 pivotscrews. 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 deviceFig.5. (a) Photo of the spherical grinding tool (b) Photo of the ball burnishing tool3. Planning of the matrix experiment3.1 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 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 analysisEngineering 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 log10(mean square quality characteristic) =10 log10where:yi : observations of the quality characteristic 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 smaller-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 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 isabout 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 parametersTable 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 factors)Measured surface roughness value (Ra)ResponsenoABCDS/N(dB)Mean111110.350.350.359.1190.350212220.370.360.388.6340.370313330.410.440.407.5970.417421230.630.650.643.8760.640522310.730.770.782.3800.760623120.450.420.397.5300.420731320.340.310.329.8010.323832130.270.250.2811.4710.267933210.320.320.329.8970.3201011220.350.390.408.3900.3801112330.410.500.436.9680.4471213110.400.390.427.8830.4031321130.330.340.319.7120.3271422210.480.500.476.3120.4831523320.570.610.534.8680.5701631310.590.550.545.0300.5601732120.360.360.358.9540.3571833230.570.530.535.2930.543Fig.7. Plots of control factor effectsThe 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 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 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 Raon 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 (2.150.45)/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 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 surfaces.Reference1 Tian Chunlin. Lapping Metal Mirror at High Speed. SPIE Vol.4223,20002 A.C Eringen. Theory of Nonlocal Elasticity and some Applications. Mechanice,21(4),19873 E.Uhimann. Surface Formation in Feed Grinding of Advanced Ceramics with and Without Ultrasonic Assistance of CIRP Vol.47(1),19984 Zhao Ji etc. Study on automatic polishing injection mold,Journal of the Society of Grinding Engineers. Vol. 39,No 4,19955 A.H. Tedric, Rolling Bearing Analysis, fourth ed., John Wiley, 20016 International Standard ISO 76, Rolling BearingsStatic Load Ratings, second ed., 1987-02-017 International Standard ISO 281, Rolling BearingsDynamic Load Ratings and Rating Life, first ed., 1990-12-018 American National Standard, ANSI/AFMA Std 9-1990, “Load Ratings and Fatigue Life for Ball Bearings”9 J.I. Amasorrain, Anlisis esttico de tornillera en coronas de orientacin. , Ikerlan (1999).10 J.I. Amasorrain, Clculo de esfuerzos en rodamientos de bolas. , Ikerlan (1997).黃河科技學(xué)院畢業(yè)(文獻(xiàn)綜述) 畢業(yè)設(shè)計(jì)(論文) 文獻(xiàn)綜述 院(系)名稱(chēng)工學(xué)院機(jī)械系 專(zhuān)業(yè)名稱(chēng)機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名 潘 其 好 指導(dǎo)教師 李 長(zhǎng) 詩(shī)2012年 03 月 10 日黃河科技學(xué)院畢業(yè)(論文)文獻(xiàn)綜述 第 9 頁(yè)研磨機(jī)設(shè)計(jì)摘要:本文介紹了研磨機(jī)的發(fā)展、研磨機(jī)的機(jī)械工作原理、類(lèi)型 、特點(diǎn)及常見(jiàn)故障等內(nèi)容。通過(guò)這些對(duì)研磨機(jī)有一個(gè)大致的了解,為設(shè)計(jì)做準(zhǔn)備。關(guān)鍵詞:研磨 平面研磨機(jī) 調(diào)速 前言:研磨是超精密加工中一種重要加工方法,其優(yōu)點(diǎn)是加工精度高,加工材料范圍廣。但傳統(tǒng)研磨存在加工效率低、加工成本高、加工精度和加工質(zhì)量不穩(wěn)定等缺點(diǎn),這使得傳統(tǒng)研磨應(yīng)用受到了一定限制。本項(xiàng)目解決了傳統(tǒng)研磨存在的絕大部分缺點(diǎn),提高了研磨技術(shù)水平,在保證研磨加工精度和加工質(zhì)量(達(dá)到了納米級(jí))的同時(shí),還顯著降低加工成本,提高加工效率,使研磨技術(shù)進(jìn)一步實(shí)用化,有利于研磨技術(shù)的推廣應(yīng)用,促進(jìn)了中國(guó)精密加工技術(shù)、先進(jìn)制造技術(shù)的進(jìn)步,增強(qiáng)中國(guó)在加工制造領(lǐng)域的競(jìng)爭(zhēng)實(shí)力,特別是對(duì)振興東北老工基地具有十分重要的現(xiàn)實(shí)意義。先進(jìn)加工制造業(yè)和光電子產(chǎn)業(yè)都是中國(guó)的特色產(chǎn)業(yè)和優(yōu)勢(shì)產(chǎn)業(yè),也是中國(guó)重點(diǎn)發(fā)展產(chǎn)業(yè),研磨加工技術(shù)對(duì)這兩個(gè)產(chǎn)業(yè)的發(fā)展都具有重要作用。本項(xiàng)目開(kāi)發(fā)的納米級(jí)高效研磨加工技術(shù)在加工效率、加工成本、加工質(zhì)量和加工精度上具有明顯的優(yōu)勢(shì),具有很好的應(yīng)用前景。研磨機(jī)是保證研磨加工的重要條件,因此人們專(zhuān)門(mén)研究了各種不同的研磨機(jī)。目前國(guó)內(nèi)生產(chǎn)高速研磨機(jī)的廠家不少,但由于研磨加工的針對(duì)性較強(qiáng),對(duì)不同的工件,研磨加工的方法也有很大的差別。所以人們研究開(kāi)發(fā)出了許多專(zhuān)用的研磨機(jī)。研磨機(jī)從加工精度上基本分為兩種。一種是加工不僅對(duì)精度要求較高并對(duì)面形精度也有所要求的工件。另外一種是加工只要求表面粗糙度的零件,例如一些鎢鋼表帶和紐扣等。這種研磨機(jī)適合加工一些尺寸較小,而且數(shù)量較大的零件。在研磨中將工件與磨料一起置入一容器內(nèi),加以振動(dòng),進(jìn)行研磨拋光。還有人專(zhuān)門(mén)研制出相應(yīng)的振動(dòng)研磨機(jī)。目前這種振動(dòng)研磨機(jī)國(guó)內(nèi)外都有廠家生產(chǎn),而且這種研磨加工技術(shù)比較成熟,應(yīng)用也日趨廣泛。1. 研磨機(jī)的發(fā)展研磨機(jī)是保證研磨加工的重要條件,因此人們專(zhuān)門(mén)研究了各種不同的研磨機(jī)。目前國(guó)內(nèi)生產(chǎn)高速研磨機(jī)的廠家不少,但由于研磨加工的針對(duì)性較強(qiáng),對(duì)不同的工件,研磨加工的方法也有很大的差別。所以人們研究開(kāi)發(fā)出了許多專(zhuān)用的研磨機(jī)。研磨機(jī)從加工精度上基本分為兩種。一種是加工不僅對(duì)精度要求較高并對(duì)面形精度也有所要求的工件。另外一種是加工只要求表面粗糙度的零件,例如一些鎢鋼表帶和紐扣等。這種研磨機(jī)適合加工一些尺寸較小,而且數(shù)量較大的零件。在研磨中將工件與磨料一起置入一容器內(nèi),加以振動(dòng),進(jìn)行研磨拋光。還有人專(zhuān)門(mén)研制出相應(yīng)的振動(dòng)研磨機(jī)。目前這種振動(dòng)研磨機(jī)國(guó)內(nèi)外都有廠家生產(chǎn),而且這種研磨加工技術(shù)比較成熟,應(yīng)用也日趨廣泛。目前國(guó)內(nèi)外生產(chǎn)后一種的廠家較多。我國(guó)在八十年代研究出來(lái)第一臺(tái)PJM320型平面研磨機(jī)。曾獲得國(guó)家科學(xué)大會(huì)獎(jiǎng)?,F(xiàn)在西安秦川發(fā)展有限公司生產(chǎn)的PJM320B就是以它為原型改進(jìn)的。在光學(xué)加工中研磨又稱(chēng)精磨,所以研磨機(jī)也稱(chēng)為精磨機(jī)。目前還有南京儀機(jī)股份有限公司生產(chǎn)的PLM-400精密拋光機(jī)。以及我國(guó)臺(tái)灣高鈺精密有限公司生產(chǎn)的各種精磨機(jī)。其中平面精磨機(jī)有DL-380和CDL-600和及CDL-900型號(hào)和雙面精磨機(jī)有CDL-4B-4L和CDL-6B-6L及CDL-9B-5L等型號(hào)。其中CDL-380型研磨機(jī)研磨精度高,可達(dá)到的平面度為0.2m0.5m,表面粗糙度Ra0.1m,它可加工各種材質(zhì)。為提高加工效率人們研制出雙面研磨機(jī),如蘭州東勝機(jī)械制造有限責(zé)任公司生產(chǎn)的DSL9B-5P型雙平面研磨機(jī),它加工出的產(chǎn)品精度為10微米級(jí),平面度及平行度在千分之一毫米。還有深圳宏達(dá)公司生產(chǎn)的雙平面研磨機(jī),其平行度及平面度也為千分之一毫米。球面高速研磨機(jī)按加工工件表面的曲率半徑不同,分為大球面、中球面和小球面三種,其中Q875型高速精磨機(jī)和QJM-40小球面高速精磨機(jī)和QJM-100中球高速研機(jī)應(yīng)用較為普遍。目前,國(guó)外高品質(zhì)的研磨機(jī)床已實(shí)現(xiàn)系列化,而且加工精度已達(dá)到很高的水平。如SPEEDFAM高速平面研磨機(jī),具有粗研磨及精研磨的廣泛研磨能力,能以短時(shí)間和低成本獲得較高的平行度、平面度以及表面粗糙度。即使不熟練的操作人員,亦能達(dá)到尺寸公差3m、平面度0.3m、平行度3m,表面粗糙度Ra0.2m以?xún)?nèi)的高精度加工水平。又如Takao NAKAMURA等人研制的硅片研磨機(jī),可同時(shí)加工5片直徑為125mm的硅片,當(dāng)硅片厚度在500515m時(shí),經(jīng)過(guò)2430min的拋光,尺寸可達(dá)到480士3m,平均材料去除率0.510.57m/min。據(jù)科技日?qǐng)?bào)2006年5月24日?qǐng)?bào)道: 納米級(jí)高效研磨加工技術(shù)主要采用固著磨料高速研磨加工方法。固著磨料高速研磨與傳統(tǒng)的散粒磨料研磨不同,其磨料的密度分布是可控的。利用固著磨料研磨的這一特點(diǎn),根據(jù)工件磨具間的相對(duì)運(yùn)動(dòng)軌跡密度分布,合理地設(shè)計(jì)磨具上磨料密度分布,以使磨具在研磨過(guò)程中所出現(xiàn)的磨損不影響磨具面型精度,從而顯著提高工件的面型精度,并且避免修整磨具的麻煩。 本項(xiàng)目將固著磨料高速研磨技術(shù)與磨具保型磨損理論和工件均勻研磨加工技術(shù)相結(jié)合,實(shí)現(xiàn)了納米級(jí)高效研磨加工,從而提高我國(guó)機(jī)械加工技術(shù)水平,特別是超精密加工技術(shù)水平。 納米級(jí)高效研磨加工技術(shù)主要適合應(yīng)用于單平面和雙平面的超精密研磨加工,其加工精度要求達(dá)到納米級(jí)水平。該技術(shù)主要是采用固著磨料高速研磨加工技術(shù),固著磨料高速研磨與傳統(tǒng)的散粒磨料研磨不同,其磨料的密度分布是可控的。利用固著磨料研磨的這一特點(diǎn),根據(jù)工件磨具間的相對(duì)運(yùn)動(dòng)軌跡密度分布,合理地設(shè)計(jì)磨具上磨料密度分布,以使磨具在研磨過(guò)程中所出現(xiàn)的磨損不影響磨具面型精度,從而顯著提高工件的面型精度,并且避免修整磨具的麻煩。在平面固著磨料研磨中,磨具的旋轉(zhuǎn)運(yùn)動(dòng)是主運(yùn)動(dòng),工件的運(yùn)動(dòng)是輔助運(yùn)動(dòng)。在大部分情況下,工件是浮動(dòng)壓在磨具上,其運(yùn)動(dòng)規(guī)律是未知的。因此,要對(duì)工件受力進(jìn)行分析,才能求出其受力狀態(tài)及運(yùn)動(dòng)規(guī)律。取工件為整個(gè)研磨系統(tǒng)的分離體,建立工件受力平衡微分方程,求解該方程就能得到工件的運(yùn)動(dòng)規(guī)律。一旦掌握了磨具和工件的運(yùn)動(dòng)規(guī)律,就可以求出它們間的相對(duì)運(yùn)動(dòng)及相對(duì)運(yùn)動(dòng)軌跡密度分布。從而根據(jù)工件相對(duì)磨具的運(yùn)動(dòng)軌跡密度分布,設(shè)計(jì)磨具上磨料密度分布,使得磨具在磨損后不喪失原有的面型精度,這就保證了工件的面型精度。 本項(xiàng)目在原有的單平面磨具保型磨損理論的基礎(chǔ)上,開(kāi)發(fā)出工件均勻研磨技術(shù),從而進(jìn)一步提高了工件的面型精度,同時(shí)還建立了固著磨料雙平面高速研磨磨具保型磨損理論,研制了雙平面高速研磨機(jī),并進(jìn)行了固著磨料雙平面高速研磨加工實(shí)驗(yàn),通過(guò)實(shí)驗(yàn)完善了有關(guān)加工工藝和研磨機(jī),實(shí)現(xiàn)了對(duì)工件的兩個(gè)平行表面同時(shí)進(jìn)行高速研磨加工。本項(xiàng)目還研究了固著磨料高速研磨中工件加工表面的形成規(guī)律,探討了有關(guān)研磨參數(shù)對(duì)工件加工表面的影響規(guī)律,并在此基礎(chǔ)上,進(jìn)一步提高了工件的表面質(zhì)量,實(shí)現(xiàn)了低成本、高效率的納米級(jí)研磨加工,工件已加工表面粗糙度達(dá)0.88nm。目前國(guó)內(nèi)外生產(chǎn)的研磨機(jī)基本上都是中大型的。對(duì)于小型便攜式高速研磨機(jī)的研究有限。而目前便攜式的研磨機(jī)只有專(zhuān)門(mén)維修閥門(mén)的維修機(jī)具。目前國(guó)內(nèi)外的高速研磨機(jī)的發(fā)展方向主要是進(jìn)一步提高研磨加工質(zhì)量和加工效率,提高研磨機(jī)的自動(dòng)化程度,以減輕操作者的勞動(dòng)強(qiáng)度。而對(duì)維修設(shè)備現(xiàn)場(chǎng)使用的便攜式研磨機(jī)還沒(méi)有人進(jìn)行研究和開(kāi)發(fā)。2. 研磨機(jī)的機(jī)械工作原理研磨機(jī)采用無(wú)級(jí)調(diào)速系統(tǒng)控制,可輕易調(diào)整出適合研磨各種部件的研磨速度。采用電氣比例閥閉環(huán)反饋 壓力控制,可獨(dú)立調(diào)控壓力裝置。上盤(pán)設(shè)置緩降功能,有效的防止薄脆工件的破碎。通過(guò)一個(gè)時(shí)間繼電器和一個(gè)研磨計(jì)數(shù)器,可按加工要求準(zhǔn)確設(shè)置和控制研磨時(shí)間和研磨圈數(shù)。工作時(shí)可調(diào)整壓力模式,達(dá)到研磨設(shè)定的時(shí)間或圈速時(shí)就會(huì)自動(dòng)停機(jī)報(bào)警提示,實(shí)現(xiàn)半自動(dòng)化操作。 研磨機(jī)變速控制方法,研磨加工有三個(gè)階段,即開(kāi)始階段、正式階段和結(jié)束階段,開(kāi)始階段磨具升速旋轉(zhuǎn),正式階段磨具恒速旋轉(zhuǎn),結(jié)束階段磨具降速旋轉(zhuǎn),其特征在于,在研磨加工開(kāi)始階段,人為控制磨具轉(zhuǎn)速的加速度從零由慢到快地增大,當(dāng)磨具轉(zhuǎn)速升到正式研磨速度的一半時(shí),加速度的變化出現(xiàn)一個(gè)拐點(diǎn),控制磨具轉(zhuǎn)速的加速度由最大值由快到慢地減小,直到磨具轉(zhuǎn)速達(dá)到正式的研磨速度,磨具轉(zhuǎn)速的加速度降為零。 利用固著磨料研磨的這一特點(diǎn),根據(jù)工件磨具間的相對(duì)運(yùn)動(dòng)軌跡密度分布,合理地設(shè)計(jì)磨具上磨料密度分布,以使磨具在研磨過(guò)程中所出現(xiàn)的磨損不影響磨具面型精度,從而顯著提高工件的面型精度,并且避免修整磨具的麻煩。在平面固著磨料研磨中,磨具的旋轉(zhuǎn)運(yùn)動(dòng)是主運(yùn)動(dòng),工件的運(yùn)動(dòng)是輔助運(yùn)動(dòng)。在大部分情況下,工件是浮動(dòng)壓在磨具上,其運(yùn)動(dòng)規(guī)律是未知的。因此,要對(duì)工件受力進(jìn)行分析,才能求出其受力狀態(tài)及運(yùn)動(dòng)規(guī)律。取工件為整個(gè)研磨系統(tǒng)的分離體,建立工件受力平衡微分方程,求解該方程就能得到工件的運(yùn)動(dòng)規(guī)律。 研磨機(jī)主機(jī)采用調(diào)速電機(jī)驅(qū)動(dòng),配置大功率減速系統(tǒng),軟啟動(dòng)、軟停止,運(yùn)轉(zhuǎn)平穩(wěn)。通過(guò)上、下研磨盤(pán)、 太陽(yáng)輪、游星輪在加工時(shí)形成四個(gè)方向、速度相互協(xié)調(diào)的研磨運(yùn)動(dòng),達(dá)到上下表面同時(shí)研磨的高效運(yùn)作。下研磨盤(pán)可升降,方便工件裝卸。氣動(dòng)太陽(yáng)輪變向裝置,精確控制工件兩面研磨精度和速度。隨機(jī)配有修正輪,用于修正上下研磨盤(pán)的平行誤差。 研磨籃式研磨機(jī)繼承了籃式研磨機(jī)分散研磨兩道工序在一臺(tái)機(jī)器、一道工序上實(shí)現(xiàn)的特點(diǎn),同時(shí)還可以作為分散機(jī)單獨(dú)使用(當(dāng)分散盤(pán)在工作位置,研磨籃未下降時(shí))。對(duì)于需要研磨的物料,又可以實(shí)現(xiàn)先分散后研磨的功能(當(dāng)研磨籃下降到工作位時(shí),可對(duì)物料進(jìn)行高效率的精研磨)。3. 研磨機(jī)類(lèi)型研磨機(jī)的主要類(lèi)型有圓盤(pán)式研磨機(jī)、轉(zhuǎn)軸式研磨機(jī)和各種專(zhuān)用研磨機(jī)。 3.1 圓盤(pán)式研磨機(jī)分單盤(pán)和雙盤(pán)兩種,以雙盤(pán)研磨機(jī)應(yīng)用最為普通。在雙盤(pán)研磨機(jī)上,多個(gè)工件同時(shí)放入位于上、下研磨盤(pán)之間的保持架內(nèi),保持架和工件由偏心或行星機(jī)構(gòu)帶動(dòng)作平面平行運(yùn)動(dòng)。下研磨盤(pán)旋轉(zhuǎn),與之平行的上研磨盤(pán)可以不轉(zhuǎn),或與下研磨盤(pán)反向旋轉(zhuǎn),并可上下移動(dòng)以壓緊工件(壓力可調(diào))。此外,上研磨盤(pán)還可隨搖臂繞立柱轉(zhuǎn)動(dòng)一角度,以便裝卸工件。雙盤(pán)研磨機(jī)主要用于加工兩平行面、一個(gè)平面(需增加壓緊工件的附件)、外圓柱面和球面(采用帶V形槽的研磨盤(pán))等。加工外圓柱面時(shí),因工件既要滑動(dòng)又要滾動(dòng),須合理選擇保持架孔槽型式和排列角度。單盤(pán)研磨機(jī)只有一個(gè)下研磨盤(pán),用于研磨工件的下平面,可使形狀和尺寸各異的工件同盤(pán)加工,研磨精度較高。有些研磨機(jī)還帶有能在研磨過(guò)程中自動(dòng)校正研磨盤(pán)的機(jī)構(gòu)。 3.2 轉(zhuǎn)軸式研磨機(jī)由正、反向旋轉(zhuǎn)的主軸帶動(dòng)工件或研具(可調(diào)式研磨環(huán)或研磨棒)旋轉(zhuǎn),結(jié)構(gòu)比較簡(jiǎn)單,用于研磨內(nèi)、外圓柱面。3.3 專(zhuān)用研磨機(jī)依被研磨工件的不同,有中心孔研磨機(jī)、鋼球研磨機(jī)和齒輪研磨機(jī)等。 此外,還有一種采用類(lèi)似無(wú)心磨削原理的無(wú)心研磨機(jī),用于研磨圓柱形工件。 4. 研磨機(jī)的特點(diǎn)(1)自動(dòng)研磨機(jī)又為高速研磨機(jī),精密研磨機(jī)。采用砂布帶,電器采用日本和泉、富士、整機(jī)噴塑,顏色為微機(jī)色;(2)導(dǎo)軌為臺(tái)灣直線(xiàn)導(dǎo)軌;(3)刮膠采取卡式鎖設(shè)計(jì),能使變形刮膠調(diào)正,確保研磨品質(zhì);(4)此自動(dòng)研磨機(jī),高速研磨機(jī),精密研磨機(jī)可用于機(jī)械式刮刀與手動(dòng)式刮刀研磨;(5)特殊研磨輪設(shè)計(jì),研磨布帶無(wú)壓力感,刮膠不變形,無(wú)波紋狀現(xiàn)象,確保研磨精度。(6)研磨角度度以配合各種特殊印刷的效能;(7)研磨機(jī)裝有洗塵裝置,可減少工業(yè)污染,有利于工作人員的身體健康及設(shè)備的保養(yǎng);(8)自動(dòng)研磨機(jī),高速研磨機(jī),精密研磨機(jī)操作簡(jiǎn)便,無(wú)需專(zhuān)業(yè)技術(shù)即可操作。5. 研磨機(jī)的小牙齒斷齒的故障研磨機(jī)在火力發(fā)電廠制粉系統(tǒng)中被廣泛的應(yīng)用,但其傳動(dòng)軸振動(dòng)及小牙輪斷齒一直困擾著系統(tǒng)的安全生產(chǎn),前一時(shí)期我廠制粉系統(tǒng)也倍受這兩個(gè)缺陷的困擾,甚至影響到了機(jī)組燃料的供應(yīng),經(jīng)檢修人員多次調(diào)整,效果顯著,傳動(dòng)軸振動(dòng)低于0.08mm。近一時(shí)期,研磨機(jī)小牙輪斷齒的故障也鮮有耳聞了,現(xiàn)將經(jīng)驗(yàn)予以總結(jié)。 具體措施: (1)齒頂間隙是齒輪傳動(dòng)裝置的重要裝配參數(shù)之一,規(guī)程中規(guī)定大、小牙輪間隙為7.5-8.5mm,實(shí)際生產(chǎn)中,設(shè)備經(jīng)長(zhǎng)期運(yùn)行,大齒輪齒圈受應(yīng)力沖擊變形,由原來(lái)的圓形漸變?yōu)闄E圓形,所以其齒頂間隙局部甚至低于6mm,在實(shí)際調(diào)整過(guò)程中應(yīng)將齒頂間隙調(diào)為8.5-10mm,以減少因齒頂間隙引起的沖擊,造成輪齒過(guò)載折斷。 (2)大齒圈的緊力不夠也是引起其變形的重要原因之一。在實(shí)際操作中,除加大螺栓緊力外,用10mm厚鋼板將大齒圈接合面連接起來(lái),加大緊固面,防止齒圈變形,保證主、從動(dòng)輪角速度一致,防止傳動(dòng)比變化引起的慣性力,造成疲勞折斷。 (3)傳動(dòng)軸軸承的充分潤(rùn)滑也是保證其平穩(wěn)運(yùn)行的主要原因,目前采用傳統(tǒng)的定期、手工加油,此舉雖也能夠保證軸承得到足夠的潤(rùn)滑,但易造成潤(rùn)滑油量的過(guò)多或不足,建議采用機(jī)械定時(shí)、定量科學(xué)地補(bǔ)充潤(rùn)滑脂,從而保證軸承的適度潤(rùn)滑,降低振動(dòng),避免軸承的磨損和保持架的破裂,延長(zhǎng)壽命。參考文獻(xiàn)1 孫恒.機(jī)械原理M七版.北京:高等教育出版社,2006.52 濮良貴,紀(jì)名剛.機(jī)械設(shè)計(jì)M八版.北京:高等教育出版社,2006.53 王愛(ài)珍.機(jī)械工程材料M.北京:北京航空航天大學(xué)出版社,2009.24 黃健求.機(jī)械制造技術(shù)基礎(chǔ)M.北京:機(jī)械工業(yè)出版社,2005.115 鄭修本.機(jī)械制造工藝學(xué)M.北京:機(jī)械工業(yè)出版社,1999.56 吳宗澤,羅圣國(guó). 機(jī)械設(shè)計(jì)課程設(shè)計(jì)手冊(cè)M. 北京:高等教育出版社,2006.57 孔慶華,母福生. 互換性與測(cè)量技術(shù)基礎(chǔ)M. 北京:同濟(jì)大學(xué)出版社,2008.98 沈鴻. 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