CA6150車床主軸箱設(shè)計(jì)【說(shuō)明書+CAD】
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畢業(yè)設(shè)計(jì)(論文)任務(wù)書
指導(dǎo)老師 錢小平
課題名稱:CA6150車床主軸箱設(shè)計(jì)
學(xué)生姓名 張斌
專業(yè)班級(jí) 數(shù)控70201班
目錄
1、 概述
2、 主運(yùn)動(dòng)的方案選擇與主運(yùn)動(dòng)的設(shè)計(jì)
3、 確定齒輪齒數(shù)
4、 選擇電動(dòng)機(jī)
5、 皮帶輪的設(shè)計(jì)計(jì)算
6、 傳動(dòng)裝置的運(yùn)動(dòng)和運(yùn)動(dòng)參數(shù)的計(jì)算
7、 主軸調(diào)速系統(tǒng)的選擇計(jì)算
8、 主軸剛度的校核
一、概述
主傳動(dòng)系統(tǒng)是用來(lái)實(shí)現(xiàn)機(jī)床主運(yùn)動(dòng)的傳動(dòng)系統(tǒng),它應(yīng)具有一定的轉(zhuǎn)速(速度)和一定的變速范圍,以便采用不同材料的刀具,加工不同的材料,不同尺寸,不同要求的工件,并能方便的實(shí)現(xiàn)運(yùn)動(dòng)的開停,變速,換向和制動(dòng)等。
數(shù)控機(jī)床主傳動(dòng)系統(tǒng)主要包括電動(dòng)機(jī)、傳動(dòng)系統(tǒng)和主軸部件,它與普通機(jī)床的主傳動(dòng)系統(tǒng)相比在結(jié)構(gòu)上比較簡(jiǎn)單,這是因?yàn)樽兯俟δ苋炕虼蟛糠钟芍鬏S電動(dòng)機(jī)的無(wú)級(jí)調(diào)速來(lái)承擔(dān),剩去了復(fù)雜的齒輪變速機(jī)構(gòu),有些只有二級(jí)或三級(jí)齒輪變速系統(tǒng)用以擴(kuò)大電動(dòng)機(jī)無(wú)級(jí)調(diào)速的范圍。
1.1數(shù)控機(jī)床主傳動(dòng)系統(tǒng)的特點(diǎn)
與普通機(jī)床比較,數(shù)控機(jī)床主傳動(dòng)系統(tǒng)具有下列特點(diǎn)。
4 轉(zhuǎn)速高、功率大。它能使數(shù)控機(jī)床進(jìn)行大功率切削和高速切削,實(shí)現(xiàn)高效率加工。
5 變速范圍寬。數(shù)控機(jī)床的主傳動(dòng)系統(tǒng)有較寬的調(diào)速范圍,一般Ra>100,以保證加工時(shí)能選用合理的切削用量,從而獲得最佳的生產(chǎn)率、加工精度和表面質(zhì)量。
6 主軸變速迅速可靠,數(shù)控機(jī)床的變速是按照控制指令自動(dòng)進(jìn)行的,因此變速機(jī)構(gòu)必須適應(yīng)自動(dòng)操作的要求。由于直流和交流主軸電動(dòng)機(jī)的調(diào)速系統(tǒng)日趨完善,所以不僅能夠方便地實(shí)現(xiàn)寬范圍無(wú)級(jí)變速,而且減少了中間傳遞環(huán)節(jié),提高了變速控制的可靠性。
7 主軸組件的耐磨性高,使傳動(dòng)系統(tǒng)具有良好的精度保持性。凡有機(jī)械摩擦的部位,如軸承、錐孔等都有足夠的硬度,軸承處還有良好的潤(rùn)滑。
1.2 主傳動(dòng)系統(tǒng)的設(shè)計(jì)要求
① 主軸具有一定的轉(zhuǎn)速和足夠的轉(zhuǎn)速范圍、轉(zhuǎn)速級(jí)數(shù),能夠?qū)崿F(xiàn)運(yùn)動(dòng)的開停、變速、換向和制動(dòng),以滿足機(jī)床的運(yùn)動(dòng)要求。
② 主電機(jī)具有足夠的功率,全部機(jī)構(gòu)和元件具有足夠的強(qiáng)度和剛度,以滿足機(jī)床的動(dòng)力要求。
③ 主傳動(dòng)的有關(guān)結(jié)構(gòu),特別是主軸組件要有足夠高的精度、抗震性,熱變形和噪聲要小,傳動(dòng)效率高,以滿足機(jī)床的工作性能要求。
④ 操縱靈活可靠, 維修方便,潤(rùn)滑密封良好,以滿足機(jī)床的使用要求。
⑤ 結(jié)構(gòu)簡(jiǎn)單緊湊,工藝性好,成本低,以滿足經(jīng)濟(jì)性要求。
1.3 數(shù)控機(jī)床主傳動(dòng)系統(tǒng)配置方式
數(shù)控機(jī)床的調(diào)速是按照控制指令自動(dòng)執(zhí)行的,因此變速機(jī)構(gòu)必須適應(yīng)自動(dòng)操作的要求。在主傳動(dòng)系統(tǒng)中,目前多采用交流主軸電動(dòng)機(jī)和直流主軸電動(dòng)機(jī)無(wú)級(jí)調(diào)速系統(tǒng)。為擴(kuò)大調(diào)速范圍,適應(yīng)低速大轉(zhuǎn)矩的要求,也經(jīng)常應(yīng)用齒輪有級(jí)調(diào)速和電動(dòng)機(jī)無(wú)級(jí)調(diào)速相結(jié)合的調(diào)速方式。
數(shù)控機(jī)床主傳動(dòng)系統(tǒng)主要有四種配置方式,如圖3-1所示。
⑴ 帶有變速齒輪的主傳動(dòng) 大、中型數(shù)控機(jī)床采用這種變速方式。如圖3-1(a)所示,通過(guò)少數(shù)幾對(duì)齒輪降速,擴(kuò)大輸出轉(zhuǎn)矩,一滿足主軸低速時(shí)對(duì)輸出轉(zhuǎn)矩特性的要求。數(shù)控機(jī)床在交流或直流電動(dòng)機(jī)無(wú)級(jí)變速的基礎(chǔ)上配以齒輪變速,使之成為分段無(wú)級(jí)變速?;讫X輪的移位大都采用液壓缸加撥叉,或者直接由液壓缸帶動(dòng)齒輪來(lái)實(shí)現(xiàn)。
⑵ 通過(guò)帶傳動(dòng)的主傳動(dòng) 如圖3-1(b)所示,這種傳動(dòng)主要應(yīng)用于轉(zhuǎn)速較高、變速范圍不大的機(jī)床。電動(dòng)機(jī)本身的調(diào)速能夠滿足要求,不用齒輪變速,可以避免齒輪傳動(dòng)引起的振動(dòng)與噪聲。它適用于高速、低轉(zhuǎn)矩特性要求的主軸。常用的是V帶和同步齒形帶。
⑶ 用兩個(gè)電動(dòng)機(jī)分別驅(qū)動(dòng)主軸 如圖3-1(c)所示,這是上述兩種方式的混合傳動(dòng),具有上述兩種性能。高速時(shí)電動(dòng)機(jī)通過(guò)帶輪直接驅(qū)動(dòng)主軸旋轉(zhuǎn);低速時(shí),另一個(gè)電動(dòng)機(jī)通過(guò)兩級(jí)齒輪傳動(dòng)驅(qū)動(dòng)主軸旋轉(zhuǎn),齒輪起到降速和擴(kuò)大變速范圍的作用,這樣就使恒功率區(qū)增大,擴(kuò)大了變速范圍,克服了低速時(shí)轉(zhuǎn)矩不夠且電動(dòng)機(jī)功率不能充分利用的缺陷。
⑷ 內(nèi)裝電動(dòng)機(jī)主軸傳動(dòng)結(jié)構(gòu) 如圖3-1(d)所示,這種主傳動(dòng)方式大大簡(jiǎn)化了主軸箱體與主軸的結(jié)構(gòu),有效地提高了主軸部件的剛度,但主軸輸出轉(zhuǎn)矩小,電動(dòng)機(jī)發(fā)熱對(duì)主軸影響較大。
1.4 主傳動(dòng)系統(tǒng)結(jié)構(gòu)設(shè)計(jì)
機(jī)床主傳動(dòng)系統(tǒng)的結(jié)構(gòu)設(shè)計(jì),是將傳動(dòng)方案“結(jié)構(gòu)化”,向生產(chǎn) 提供主傳動(dòng)部件裝配圖,零件工作圖及零件明細(xì)表等。
在機(jī)床初步設(shè)計(jì)中,考慮主軸變速箱機(jī)床上位置,其他部件的相互關(guān)系,只是概略給出形狀與尺寸要求,最終還需要根據(jù)箱內(nèi)各元件的實(shí)際結(jié)構(gòu)與布置才確定具體方案,在可能的情況下,設(shè)計(jì)應(yīng)盡量減小主軸變速箱的軸向和徑向尺寸,以便節(jié)省材料,減輕質(zhì)量,滿足使用要求。設(shè)計(jì)中應(yīng)注意對(duì)于不同情況要區(qū)別對(duì)待,如某些立式機(jī)床和搖臂鉆床的主軸 箱;要求較小的軸向尺寸而對(duì)徑向尺寸要求并不嚴(yán)格;但有的機(jī)床,如臥式銑鏜床、龍門銑床的主軸箱要沿立柱或橫梁導(dǎo)軌移動(dòng),為減少其顛覆力矩,要求縮小徑向尺寸。
機(jī)床主傳動(dòng)部件即主軸變速箱的結(jié)構(gòu)設(shè)計(jì)主要內(nèi)容包括:主軸組件設(shè)計(jì),操縱機(jī)構(gòu)設(shè)計(jì),傳動(dòng)軸組件設(shè)計(jì),其他機(jī)構(gòu)(如開停、制動(dòng)及換向機(jī)構(gòu)等)設(shè)計(jì),潤(rùn)滑與密封裝置設(shè)計(jì),箱體及其他零件設(shè)計(jì)等。
主軸變速箱部件裝配圖包括展開圖、橫向剖視圖、外觀圖及其他必要的局部視圖等。給制展開圖和橫向剖視圖時(shí),要相互照應(yīng),交替進(jìn)行,不應(yīng)孤立割裂地設(shè)計(jì),以免顧此失彼。給制出部件的主要結(jié)構(gòu)裝配草圖之后,需要檢查各元件是否相碰或干涉,再根據(jù)動(dòng)力計(jì)算的結(jié)果修改結(jié)構(gòu),然后細(xì)化、完善裝配草圖,并按制圖標(biāo)準(zhǔn)進(jìn)行加深,最后進(jìn)行尺寸、配合及零件標(biāo)注等。
二、主運(yùn)動(dòng)的方案選擇與主運(yùn)動(dòng)設(shè)計(jì)
1、機(jī)床的工藝特性
1.1 工藝范圍
精車、半精車外圓、車螺紋、車端面
1.2 刀具材料
硬質(zhì)合金、高速鋼
1.3 加工工作材料
鋼、鑄鐵
1.4 尺寸范圍
0~500㎜
2、確定主軸轉(zhuǎn)速
2.1 最高轉(zhuǎn)速 nmax
采用硬質(zhì)合車刀半精車小直徑鋼材的外圓時(shí),主軸轉(zhuǎn)速最高。參考切削用量資料:
Vmax =150~200 m/s K = 0.5 Rd =0.2~0.25
dmax =K·D =0.5×400 =200㎜
dmin =Rd ·dmax =0.2×200 =40㎜
nmax = = =1592.36
2.2最低轉(zhuǎn)速:
①用高速鋼車刀,粗車鑄鐵材料的端面時(shí),參考切削用量資料:
Vmax =15~20 m/s
nmin = = =31.8
②用高速鋼車刀,精車合金鋼材料的絲杠時(shí),參考資料:
直徑500㎜普通車床加工絲杠的最大直徑是50㎜,
Vmin =1.5 米/分
nmin = = =11.9轉(zhuǎn)/分
因此:取最低轉(zhuǎn)速nmin=11.9轉(zhuǎn)/分
③轉(zhuǎn)速范圍
Rn= ==133.8
由于高速鋼車刀少用低速,且為了避免結(jié)構(gòu)過(guò)于復(fù)雜,因此取轉(zhuǎn)速范圍Rn=1592.36/31.8=50
④主運(yùn)動(dòng)結(jié)構(gòu)圖
三、確定齒輪齒數(shù)
1、 根據(jù)分度圓直徑選齒數(shù): d=mz
a組: Za1 = 64
Za2 = 54
Z = 34
b組:
Zb1 = 95
Zb2 = 30
2、 齒輪的各參數(shù)
a組:
模數(shù)m = 4
壓力角 α=20°
齒距 P = πm =12.56
齒厚 s = πm/2 = 6.28
齒槽寬 e =πm/2 = 6.28
頂隙 c = cm =1.2
齒頂高 h = hm = 4
齒根高 h = (h+ c)m = 5.2
全齒高 h = h+ h=(2h+ c)m = 9.2
中心距 a1 = (d1+d2)/2 = 240
a2 = (d1+d3)/2 = 178
b組: 模數(shù)m = 3.5
壓力角 α=20°
齒距 P = πm =12.56
齒厚 s = πm/2 = 6.28
齒槽寬 e =πm/2 = 6.28
頂隙 c = cm =1.2
齒頂高 h = hm = 4
齒根高 h = (h+ c)m = 5.2
全齒高 h = h+ h=(2h+ c)m = 9.2
中心距 a = (d4+d5)/2 = 240
四、選擇電動(dòng)機(jī)
1、 電動(dòng)機(jī)功率
N電=7.5kw 轉(zhuǎn)速n電=1450轉(zhuǎn)/分
2、 電機(jī)型號(hào)
J02—51—4 電機(jī)軸徑=38㎜
五、皮帶輪的設(shè)計(jì)計(jì)算:
設(shè)一天運(yùn)轉(zhuǎn)時(shí)間=8~10小時(shí)(按小帶輪計(jì)算)
1、 計(jì)算功率Pc = KA·P = 1.2×7.5 = 9kw
2、 選膠帶型別為:B型
3、 選小帶輪直徑d1=140㎜(實(shí)心輪)
大帶輪直徑d2=280㎜(四孔板輪)
4、 帶速:
V===10.6米/秒
(B型:Vmax=25米/秒)
5、 實(shí)際傳動(dòng)比:
i= 取ε=005
i==4<7
6、 初定中心距
=(1~0.95)d2=(1~0.95)×280=280~266
取=270
7、 初定膠帶節(jié)線長(zhǎng)度
Lop=2+(d1+d2)+
=2×270+×(140+280)+
=1218
取Lp=1290 Li=1250
8、 計(jì)算中心距
=+=270+=306㎜
9、 小帶輪包角
≈180°-×60°
=180°-×60°=152.5°>120°
10、 單根膠帶傳遞的功率:
P0=2.03kw
11、 單根膠帶傳遞功率的增量:
ΔP0=kb·n1·(1-)
=1.99×10×1450×(1-)
=2.8
12、 膠帶根數(shù):
由于需要傳遞的功率N=7kw, 因此需膠帶4根
13、 單根膠帶初拉力: F0=18公斤
14、 有效圓周力: Ft===91.8公斤
15、 作用在軸上的力:
F=2F0·Z·sin=2×18×4×sin
=134公斤
16、 帶輪寬:
B=(Z-1)e+2f=(4-1)×20+2×12.5=85㎜
六、 傳動(dòng)裝置的運(yùn)動(dòng)和運(yùn)動(dòng)參數(shù)計(jì)算:
1、傳動(dòng)比:
i= 1.19
2、傳動(dòng)裝置的運(yùn)動(dòng)參數(shù):
Ⅰ軸(電動(dòng)機(jī)軸):
P=Pd=7.5 kw
n=1450r/min
T=9550×=9550×=49.4 N·m
Ⅱ軸(主軸):
P= Pη=7.5×0.96=7.2 kw
n= = = 1218 r/min
T=9550×=9550×=56.45 N·m
Ⅲ軸(編碼器):
P= Pη=7.2×0.99×0.97=6.9 kw
n= = = 766 r/min
T=9550×=9550×=86.02 N·m
七、 主軸調(diào)速系統(tǒng)的選擇計(jì)算
1、 對(duì)調(diào)速系統(tǒng)的基本考慮:
a.由于調(diào)速范圍廣,且要求有較硬的機(jī)械特性。所以,以選用矢量控制方式為宜。對(duì)于普通車床來(lái)說(shuō),由于對(duì)動(dòng)態(tài)響應(yīng)要求不高,用“無(wú)反饋矢量控制”方式已經(jīng)足夠。
b.因?yàn)檎{(diào)速范圍廣,且高速與低速段機(jī)械特性的特點(diǎn)不一樣,故工作頻率范圍應(yīng)不限于額定頻率以下。
c.電動(dòng)機(jī)的容量一般應(yīng)比原拖動(dòng)系統(tǒng)的電動(dòng)機(jī)容量為大。
d.在低速段,可能出現(xiàn)較大的沖擊過(guò)載,容易引起變頻器的跳閘。所以,變頻器的容量以比電動(dòng)機(jī)的容量大一檔為好。
2、 一檔傳動(dòng)比,且方案
基本工作情況
a. 電動(dòng)機(jī)和主軸之間的傳動(dòng)比只有一檔,傳動(dòng)比
b. 變頻器的最大輸出頻率等于電動(dòng)機(jī)的額定頻率。從而,電動(dòng)機(jī)的最高轉(zhuǎn)速等于其額定轉(zhuǎn)速,它折算到負(fù)載軸上的值應(yīng)大于負(fù)載要求的最大轉(zhuǎn)速:
=
c. 電動(dòng)機(jī)額定轉(zhuǎn)矩的折算值(折算到負(fù)載軸上的轉(zhuǎn)矩);
綜上所述,電動(dòng)機(jī)的有效轉(zhuǎn)矩線如圖3.2的曲線2所示,
圖3.2
曲線1是車床的機(jī)械特性曲線。為了便于比較,
圖中,電動(dòng)機(jī)的轉(zhuǎn)矩和轉(zhuǎn)速均為折算到負(fù)載軸上的值。
電動(dòng)機(jī)的容量在圖3.2中,負(fù)載所需功率
其大小與面積成正比。而電動(dòng)機(jī)的容量則與面積成正比,其大小為:
可見,采用了變頻調(diào)速后,電動(dòng)機(jī)的容量需增大倍以上。
3、 電動(dòng)機(jī)的工作頻率范圍
a. 最高頻率。
b. 最底頻率因?yàn)橹挥幸粰n轉(zhuǎn)速,故頻率調(diào)節(jié)范圍為:
當(dāng)時(shí), ;
當(dāng)時(shí),。
異步電動(dòng)機(jī)在這樣低的頻率下連續(xù)工作,如不用負(fù)載反饋,是比較困難的。
4、 一檔傳動(dòng)比,且方案
基本工作情況
a. 電動(dòng)機(jī)和主軸之間的傳動(dòng)比仍只有一檔,但變頻器的最高輸出頻率
允許超過(guò)額定頻率。但一般不宜超過(guò)額定頻率的1.5倍(即:).
設(shè)最大調(diào)頻比
則:電動(dòng)機(jī)的最高轉(zhuǎn)速也約為額定轉(zhuǎn)速的倍:
b. 電動(dòng)機(jī)的額定轉(zhuǎn)速
電動(dòng)機(jī)有效轉(zhuǎn)矩線圈如圖中的曲線2所示。曲線1為車床的機(jī)械特性曲線。
電動(dòng)機(jī)的容量如圖,電動(dòng)機(jī)的容量與面積成正比,其大小為
可見,頻率范圍擴(kuò)大之后,電動(dòng)機(jī)的容量可 以比減小倍,但與負(fù)載功率相比,仍需增大很多。
5、 電動(dòng)機(jī)的工作頻率范圍
設(shè):最高頻率為,則最低頻率為
當(dāng)時(shí),;
當(dāng)時(shí),。
6、兩檔傳動(dòng)比,且方案
基本工作情況
將電動(dòng)機(jī)和主軸之間的傳動(dòng)比分成兩檔(和),使變頻器的輸出頻率、電動(dòng)機(jī)的轉(zhuǎn)速與負(fù)載轉(zhuǎn)速之間的對(duì)應(yīng)關(guān)系見表4-1
表4-1 頻率、電動(dòng)機(jī)與負(fù)載轉(zhuǎn)速之間的對(duì)應(yīng)關(guān)系
工作頻率
電動(dòng)機(jī)的轉(zhuǎn)速
低檔傳動(dòng)比
負(fù)載轉(zhuǎn)速
高檔傳動(dòng)比
負(fù)載轉(zhuǎn)速
表中,是兩檔轉(zhuǎn)速分界點(diǎn)的“中間速”。在抵擋時(shí),傳動(dòng)比為,當(dāng)從
到(到)時(shí),從到;在高檔時(shí),傳動(dòng)比為,當(dāng)從到 (從到)時(shí), 從到。
忽略電動(dòng)機(jī)轉(zhuǎn)差率的變化的因素,則有:
圖3.3
作為兩檔中間的分界轉(zhuǎn)速(中間速)
所以,電動(dòng)機(jī)工作頻率的范圍
可見,采用兩檔傳動(dòng)比后,在負(fù)載的速度范圍不變的情況下,工作頻率的調(diào)節(jié)范圍大大的縮小了。采用兩檔傳動(dòng)比后,在全頻率范圍內(nèi)的有效轉(zhuǎn)矩線如圖3.3中之曲線2所示,曲線1為車床的機(jī)械特性曲線。可以看出兩者已經(jīng)十分接近了。
7 、動(dòng)機(jī)的容量
電動(dòng)機(jī)的容量與面積成正比,如圖3所示。其大小為:
可見,采用兩檔傳動(dòng)比后,電動(dòng)機(jī)容量可比減小倍。
電動(dòng)機(jī)的工作頻率范圍
設(shè):最高頻率為,則最低頻率為
當(dāng)時(shí)
當(dāng)時(shí)
可見,最低工作頻率增大了很多,使變頻調(diào)速系統(tǒng)在最低速時(shí)的工作穩(wěn)定性大大改善了.
8、 調(diào)速系統(tǒng)的選擇
經(jīng)上述分析,主軸拖動(dòng)系統(tǒng)在不更換電動(dòng)機(jī)的條件下,要實(shí)現(xiàn)主軸轉(zhuǎn)速的無(wú)級(jí)調(diào)速,可以采用機(jī)械多檔變速傳動(dòng),與變頻器調(diào)速相結(jié)合的方法。
原拖動(dòng)與系統(tǒng)概況。
電動(dòng)機(jī)的主要數(shù)據(jù)
電動(dòng)機(jī)額定功率:7.5KW
電動(dòng)機(jī)額定轉(zhuǎn)速:1450rpm
主軸轉(zhuǎn)速范圍:10—2000r/min
計(jì)算數(shù)據(jù)
a. 調(diào)速范圍
b. 負(fù)載轉(zhuǎn)矩
n/(r/min)
1.恒轉(zhuǎn)矩區(qū)的最大轉(zhuǎn)速
143.25
T/(N/m)
35.8
500
2000
2.恒轉(zhuǎn)矩區(qū)的轉(zhuǎn)矩
3.恒功率區(qū)的最小轉(zhuǎn)矩
3.3.9普通籠型異步電動(dòng)機(jī)變頻調(diào)速運(yùn)行時(shí)的性能分析
普通籠型異步電動(dòng)機(jī)是按工頻電源條件下運(yùn)行所設(shè)計(jì)制造的,用變頻器對(duì)其進(jìn)行調(diào)速時(shí),因變頻器輸出波形中含有諧波的影響,電動(dòng)機(jī)功率因數(shù)、效率均有下降,電流與線圈溫升將有所增高,電機(jī)在額定頻率以下連續(xù)進(jìn)行時(shí),影響其帶負(fù)載能力的主要因素是溫升,在額定頻率以上連續(xù)運(yùn)行時(shí),電機(jī)允許最高頻率受軸承的極限轉(zhuǎn)速、旋轉(zhuǎn)件的強(qiáng)度限制,因此初步選定電機(jī)的變頻范圍在10Hz~75Hz之間。最大頻率調(diào)節(jié)比
因此在不變換主軸電機(jī)的條件下,主軸拖動(dòng)系統(tǒng)需采用機(jī)械三檔以上變速傳動(dòng)比在機(jī)械結(jié)構(gòu)上,三檔與四檔變速傳動(dòng)的方案相似,而采用四檔變速對(duì)電機(jī)的調(diào)速更為合適,因此決定利用機(jī)械四檔變速傳動(dòng)方案。
確定傳動(dòng)比
拖動(dòng)系統(tǒng)機(jī)械四檔變速分配
傳動(dòng)比
檔次
低
中
高
最高
電機(jī)
工作區(qū)
恒轉(zhuǎn)矩
恒功率
恒轉(zhuǎn)矩
恒功率
恒轉(zhuǎn)矩
恒功率
恒轉(zhuǎn)矩
恒功率
主軸轉(zhuǎn)速r/min
10 50
50
72.5
72
360
360
540
540
1080
1080
1620
1620
1800
1800
2160
電機(jī)
頻率Hz
10
50
50
75
10
50
50
75
22.5 50
50
75
45
50
50
55
電機(jī)轉(zhuǎn)r/min
290
1450
1450
2175
290
1450
1450
2175
725
1450
1450
2175
1305
1450
1450
1595
低速傳動(dòng)比
取
中速傳動(dòng)比
取
高速傳動(dòng)比
取
最高速傳動(dòng)比
取
電機(jī)負(fù)荷性能核算
恒轉(zhuǎn)矩區(qū)折算至負(fù)載軸的轉(zhuǎn)矩
恒功率區(qū)折算至負(fù)載軸的轉(zhuǎn)矩
、、、調(diào)整后。拖動(dòng)系統(tǒng)機(jī)械四檔調(diào)速分配及帶負(fù)載核算如下表:
傳動(dòng)比
檔次
低
中
高
最高
電機(jī)
工作區(qū)
恒轉(zhuǎn)矩
恒功率
恒轉(zhuǎn)矩
恒功率
恒轉(zhuǎn)矩
恒功率
恒轉(zhuǎn)矩
恒功率
主軸轉(zhuǎn)速r/min
10
50
50
72.5
72
360
360
540
540
1080
1080
1620
1620
1800
1800
2160
電機(jī)
頻率Hz
10
50
50
75
10
50
50
75
22.5
50
50
75
45
50
50
55
電機(jī)轉(zhuǎn)速r/min
290
1450
1450
2175
290
1450
1450
2175
725
1450
1450
2175
1305
1450
1450
1595
電機(jī)
調(diào)頻比
0.2
1
1
1.5
0.2
1
1
1.5
0.5
1
1
1.5
0.9
1
1
1.1
折算
轉(zhuǎn)矩N·M
1432.5
1432.5
955
198
198
132
66
66
44
39
39
36
核算結(jié)果表明:在不變換主軸電機(jī)的條件下,主軸拖動(dòng)系統(tǒng)采用機(jī)械四檔變速傳動(dòng)比的方案滿足要求。
注:
狀態(tài)
輸入
低檔(K10)
中檔(K11)
高檔(K12)
最高檔(K10、K12)
SQ15
1
0
0
1
SQ16
0
1
0
0
SQ17
0
0
1
1
八、主軸鋼度的校核
1、 計(jì)算切削力和驅(qū)動(dòng)力
① 切削力的計(jì)算(Pz)
a、切削功率:N切=NⅣ·=6.3×0.98=6.05kw
b、切削轉(zhuǎn)矩:M=9550×=9550×=638.7N·M
c、切削力:Pz= 取=130
Pz==9.8×10N
d、Py=0.4Pz=0.4×9.8×10=3.92×10N
Px=0.25Pz=0.25×9.8×10=2.45×10N
② 驅(qū)動(dòng)力的計(jì)算(Qr)
a、 齒輪的傳遞功率
N齒= NⅣ·η齒=6.57×0.98=6.44kw
b、 齒輪的傳遞轉(zhuǎn)距
M=9550×=9550×=173.3N·m
c、 驅(qū)動(dòng)力 QT===4304.2N
Qr= QT·tgα=4304.2×tg20°=1566.6N
③ 切削力Pz與驅(qū)動(dòng)力QT的位置關(guān)系,由機(jī)床個(gè)軸位置布置關(guān)系可知:
β=20°
Qz=QTcosβ+Qrsinβ=4304.2×cos20°+1566.6×sin20°=4580.4N
Qy=QTsinβ-Qrcosβ=4304.2×sin20°-1566.6×cos20°=0
2、 主軸的受力分析
① Z方向
三軸承支撐可簡(jiǎn)化為如圖所示靜不定系統(tǒng)
式中: 卡盤長(zhǎng)L卡=150㎜
工件長(zhǎng)LⅠ=160㎜
a=100㎜ b=65㎜ c=456㎜
L1=285㎜ L2=236㎜ L=521㎜
Mz=Pz(L卡+ LⅠ)=9800×(150+160)=3.038×10N·㎜
E=2.1×10
I=(D平-d)=3870571.2
a、 在Pz作用下,B處的撓度:
(yB)Pz=
b、 在Mz作用下,B處的撓度:
(rB)MZ=
c、 在QZ作用下,B處的撓度:
(YB)QZ=-
所以YB=+-
d、 在(RB)Z作用B處的撓度:
(Y′B)=
由于B處軸承是剛性支承
所以YB= Y′B
+-
=
由上式可求出(RB)Z
(RB)Z=
=22330N
② r方向:
三軸承支承可簡(jiǎn)化為如圖所示靜不定系統(tǒng):
(RB)y=
式中:My=Py·(L卡+ LⅠ)=1215200N·㎜
Mx=Px·=147000N·㎜
Qy=0
(RB)y=10510.5N
3、 主軸撓度計(jì)算:
① Z方向
Y=--++
=-[9800×100×(521+100)
+--
=-0.06
② Y方向
Y=---+
=-[3920×100×(521+100)
+ -]
=-0.025
③ 計(jì)算總撓度:Y===0.065
[Y]=0.002l=0.002×521=0.104
計(jì)算結(jié)果:Y〈[Y] 主軸撓度合格
4、 軸承處轉(zhuǎn)角的校核
① Z方向:
Qz=+-
其中:a′=a+ l卡+ lⅠ=100+150+160=410㎜
Qz=-0.00033
② Y方向:
Qy=--;( Qy=0)
=-0.00012
③ 計(jì)算總轉(zhuǎn)角
Q==0.00035〈0.001rad
因此機(jī)床主軸的剛度是合適的
畢業(yè)設(shè)計(jì)
開題報(bào)告書
題 目
姓 名
張斌
學(xué) 號(hào)
專 業(yè)
數(shù)控技術(shù)
指導(dǎo)教師
錢小平
職 稱
2007 年 11 月
課題來(lái)源
對(duì)數(shù)控機(jī)床傳動(dòng)系統(tǒng)的觀察,及自己的興趣愛好,對(duì)數(shù)控車傳動(dòng)系統(tǒng)產(chǎn)生了濃厚的興趣?,F(xiàn)在決定以此為課題,進(jìn)行CA6150主軸傳動(dòng)系統(tǒng)系統(tǒng)的設(shè)計(jì)。
科學(xué)依據(jù)(包括課題的科學(xué)意義;國(guó)內(nèi)外研究概況、水平和發(fā)展趨勢(shì);應(yīng)用前景等)
MPS模塊化生產(chǎn)系統(tǒng)具有較好的柔性,即每站各有一套PLC控制系統(tǒng)獨(dú)立控制,且結(jié)構(gòu)簡(jiǎn)單,功能明確,模擬性強(qiáng),操作簡(jiǎn)便;安裝與調(diào)整方便,制造與檢測(cè)容易。
研究?jī)?nèi)容
目前要解決如下問(wèn)題:
電動(dòng)機(jī)功率的確定、滑道角度的確定、氣缸型號(hào)的選擇機(jī)器及材料的確定。
現(xiàn)基本以機(jī)械設(shè)計(jì)為主,其它為輔。
擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析
(1) 設(shè)計(jì)滿足本站功能要求的自動(dòng)機(jī)械裝置,包括氣動(dòng)回路;
(2) 根據(jù)需要選擇(或設(shè)計(jì))原動(dòng)機(jī)、傳動(dòng)機(jī)構(gòu)、執(zhí)行元件;
(3) 繪制本站全套機(jī)械工程圖(裝配圖和零件圖)一份;
(4) 撰寫設(shè)計(jì)計(jì)算說(shuō)明書一份。
研究計(jì)劃及預(yù)期成果
MPS是模擬生產(chǎn)系統(tǒng)(Model Produce System)的英文縮寫,用于模擬一個(gè)典型的順序控制系統(tǒng)。模塊化MPS是用于自動(dòng)化專業(yè)高級(jí)維修電工進(jìn)行PLC編程與操作以及PLC聯(lián)網(wǎng)控制技能訓(xùn)練的教學(xué)設(shè)備。
整個(gè)模塊化MPS是由上料檢測(cè)站、搬運(yùn)站、加工站、安裝站、安裝搬運(yùn)站、分類站六個(gè)部分組成的。故每一站除了要求能單獨(dú)完成本站的一個(gè)動(dòng)作過(guò)程(功能要求)外,還要考慮能將各站按一定順序聯(lián)接在一起,組成一個(gè)模塊化生產(chǎn)系統(tǒng)。
特色或創(chuàng)新之處
這兩個(gè)系統(tǒng)的設(shè)計(jì)特點(diǎn)是模塊化,結(jié)構(gòu)簡(jiǎn)單,模擬性強(qiáng),操作簡(jiǎn)便。每一站就是一個(gè)模塊,各自有一套獨(dú)立的功能。兩模塊之間又能相互聯(lián)系,構(gòu)成一個(gè)的“系統(tǒng)工程”。是一臺(tái)較理想的理論知識(shí)和技能訓(xùn)練相結(jié)合的教學(xué)設(shè)備,非常適合高等職業(yè)技術(shù)學(xué)校進(jìn)行模塊化教學(xué)。
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在本次MPS上料檢測(cè)站和搬運(yùn)站機(jī)械設(shè)計(jì)中,主要解決的問(wèn)題是材料的選擇以及汽缸的選擇;其次是對(duì)傳感器的選擇。
由于學(xué)校在自動(dòng)化設(shè)計(jì)方面的資料比較多,以及在網(wǎng)上找到的資料。故本次設(shè)計(jì)的資料比較齊全。
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A GRINDING SPINDLE D. Broadley, describes the factors influencing the design and then tells how to make a grinding spindle head. Part 1 Model Engineer 19 June 1992 Part 2 7 July 1992, Part 3 21 August 1992 The real heart of a good machine tool stems from the quality of its machine spindle. The lathe is a prime example of this statement, the lathe spindle having a particularly heavy duty to perform even in a light duty machine. However the model engineer has a requirement for a variety of light but precise machine spindles which are, with care, within the capability of the average amateur and of modest cost. This series of articles will deal mainly with the design and manufacture of a light but precise grinding spindle but will finally extend the exercise to the design of a unit capable of carrying an MT2 spindle of somewhat greater load carrying capacity. The design principles are however the same. The Grinding Spindle Much has already been written on the subject of grinding spindle head design, and it is difficult to state anything which has not been said or written before. However it is necessary to state the design principles involved. What we are after is a 4800 rpm free running and accurate spindle without end float in order basically to ensure stability of the grinding wheel. The loads involved are very low apart from loads in the grinding wheel itself and any preloads we must build into the spindle to ensure stability. These latter are also low but important to get right. Finally we need to be able to replace wheels easily and accurately in order to avoid regrinding and hence wheel wastage every time we change a wheel. The satisfaction of making such a spindle which, apart from the wheel itself, looks as though it is stationary is reward enough for the effort involved apart from the fact that we finish up with a most universally useful tool. The main element of our grinding spindle is to choose the correct bearings in an accurately machined housing with correct internal preload. All preloads consists of is a method of spring loading one of the two ball races to adjust end float caused by axial tolerances (the difficulty of accurately measuring the distance between the inner races on the shaft and outer races in the housing) and any differential thermal expansion as inevitably one part of the spindle achieves working temperatures compared with another. A good high speed spindle is that critical. The bearings chosen are relatively inexpensive angular contact or magneto type which lend themselves particularly well to simple and practical methods of preload. There are numerous ways of providing the necessary preload but the one chosen here is what I consider to give the most reliable and, for the amateur the simplest and least expensive method. It is based on bearing disc springs which are readily available and which cover the complete range of sizes for the projects in hand. They can be obtained through the many bearing factors in most large towns and also are available from N.S.&A. Hemingway. The spring characteristic for single and multi-stacked discs is shown in Fig. 1. it being necessary to use 4 springs for this application in order to achieve the preload of 5 to 6 lbs requiring a compression of 15 to 20 thou respectively, but more about this later. Enough of the preamble, how do we go about making it! Fig. 2 shows an exploded view of the system. The casing, spindle and the bearing spacer require some fairly accurate machining so take your time. Free cutting mild steel is recommended throughout for which well ground HSS tools are quite capable of giving the accuracy and finish that we require. The extent to which strength is lost due to addition of a trace of lead is so small in the vast majority of model applications I am amazed that it is not more widely used and available. It is perfectly adequate for this project and its advantages in machineability is in my view outstanding. Drawing 1 Starting with the spindle housing (Item 1) mount one end in the 4 jaw and the other in the fixed steady end true it up with the D.T1. after cleaning off any rust etc. from the outer diameter. This arrangement is shown in Photo 2 part 2. You should be able to achieve a very few tenths (of a thou.) with care. Drill the casing through and bore it out to 1.25 in. at least half way and preferably through. Carefully bore for the outer ball race. If you are using a magneto bearing the outer race is separable and can be used as a reference if this helps (carefully clean it afterwards). The bore you need for a light push fit is only 3 tenths smaller than the outside of the bearing. You can bore for a 0.002 in. clearance and use Loctite if you wish. I personally go for a light push fit every time but if a mistake is made I would not hesitate to use the remarkable Loctite products, in this case Loctite 64 Bearing Fit. Next thread the end 32 TPI x in, before turning the casing round, truing it up again with the D.T.I. and repeating the procedure from the other end but this time making the outer race a nice sliding fit in the casing. Finally thread what is the drive end 32 TPI also. Just a word on screwcutting in the lathe. The depth of thread for 32 TBI Whitworth form is 0.031 in. but if you are using a pointed screwcutting tool, most do, do not forget to add on the extra sixth for the bottom of the thread i.e. the actual depth of thread is 0.036 in. The spindle (Item 2) is handled in a similar way to the casing but from a piece of 1 in. OD FCMS and leaving sufficient length to machine the complete spindle, hold it in the 3 jaw and centre the free end using the fixed steady. Remove the steady and using a rotating centre carefully turn the whole of the outside of the spindle including the 7/8 in. nose. Unless you use Loctite you will require great care to achieve the necessary light push fit since the interference you require on this small diameter is only a tenth of a thou. or so but this is only necessary where the bearings locate. Lapping, which in my view docs not receive the attention it deserves, is the best way of achieving the accuracy required. If you use Loctite NOT YET. Screwcut the in. x 32 TPI thread in the lathe, finishing it off with a die. Next fit the fixed steady, not over the bearing location, and remove the centre. The 3/8 in. bore we are going to tackle next is accomplished by truing up the spindle, now in a fixed steady, with the D.T.l. and bore the spindle to 3/8 in. by step drilling, preferably making the final cut with the D bit. The bore is long and you are unlikely to have a long enough drill to go right through. So reverse the spindle and again using the fixed steady on the 7/8 in. nose true the outside as accurately as possible with the D.T.1. then, drill until the bores meet, leaving the last say 20 thou, to the D bit. You really can do this without being able to see the join. All that needs to be done to finish the nose is to machine the 40 deg. taper. This I did quite successfully at the same setting but you may choose to follow the procedure of Professor Chaddock in his excellent book on the Quorn Tool and Cutter Grinder. In this the whole of the spindle housing is held in the in the fixed steady, the spindle itself being driven in the preloaded bearings. I cannot fault this method but feel that beginners at least will find the method that I have outlined to be satisfactory. The necessary skill to true up a component in the lathe to the accuracies required is not that difficult, but take your time. Next tackle the bearing spacer (Item 4) to a slide fit on the spindle. The length of the tube is fairly critical to maintain the differential between the housing and the length of the spacer. This differential must be 0.168 in. to 0.173 in, to give a preload of 6 to 5 lbs. respectively. This necessitates some simple arithmetic involving measuring the length of the housing, subtracting the outer bearing recess dimensions and adding 0.173 in. as shown on the drawing to obtain the length of the spacer. You must check it this way because it is almost certain that you will not have controlled the length scales accurately enough. If you use an angular contact bearing, which are cheaper and more readily available than magneto bearings, it is necessary to adjust the length scales because they are 3mm wider, i.e. 11mm wide. Ensure that the ends of the spacer are parallel when machining it to length by supporting it in the fixed steady and again check with the D.T.I. The spacer tube is reduced at the disc spring end in order to support the stack. This diameter is important but not critical to provide the correct internal support for the disc spring stack. To repeat the length of the spacer is important as it automatically gives the correct preload and for these particular disc springs 1 lb preload = 0.004 inch. A simple way of measuring the housing and bearing recesses in order to achieve the correct length of the bearing spacer is given later. Finally make the screwed end caps which are identical. There are other ways to retain the spindle and contain the oil or grease than screwed end caps and oil seals which I have shown on the drawing. Oil seals of the full bearing diameter are readily available but in my case I was anxious to provide the maximum spacing between the bearing and the design shown does this nicely. I also machined thin brass washers between the casing and the end caps which add a decorative as well as useful oil retaining role. Whichever type of seal you use it is advisable to lap the seating to speed running in and minimum wear on the seal lip. The oil seals do unfortunately give significant drag particularly when new. A light grease rather than oil and either a lapped fit or felt seal are I am sure perfectly good alternatives. The bearings are good for 20,000 rpm with grease and 25.000 rpm with oil, but please not with a grinding wheel on it. The absolute need to keep within the rpm limit of the largest wheel cannot be over emphasized (the maximum speed is stamped by law on all but the very small wheels).
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