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沖壓模具設(shè)計(jì)中對(duì)機(jī)械運(yùn)動(dòng)的控制和運(yùn)用
在沖壓過程中,機(jī)械運(yùn)動(dòng)貫穿始終。各種沖壓工藝的實(shí)現(xiàn)都有其基本運(yùn)動(dòng)機(jī)理,這種運(yùn)動(dòng)是與模具密切相關(guān)的,各種模具的結(jié)構(gòu)設(shè)計(jì)和力學(xué)設(shè)計(jì)最終都是為了滿足其能夠?qū)崿F(xiàn)特定運(yùn)動(dòng)的要求。設(shè)計(jì)的模具能否嚴(yán)格完成實(shí)現(xiàn)沖壓工藝所需的運(yùn)動(dòng),直接影響到?jīng)_壓件的品質(zhì),所以在模具設(shè)計(jì)中應(yīng)對(duì)機(jī)械運(yùn)動(dòng)進(jìn)行控制。同時(shí)為了達(dá)到產(chǎn)品形狀尺寸的要求,不能夠拘泥或局限于各種工藝基本運(yùn)動(dòng)模式中,而應(yīng)不斷發(fā)展和創(chuàng)新,在模具設(shè)計(jì)中對(duì)機(jī)械運(yùn)動(dòng)靈活運(yùn)用。摘要:在沖壓過程中,機(jī)械運(yùn)動(dòng)貫穿始終。各種沖壓工藝的實(shí)現(xiàn)都有其基本運(yùn)動(dòng)機(jī)理,這種運(yùn)動(dòng)是與模具密切相關(guān)的,各種模具的結(jié)構(gòu)設(shè)計(jì)和力學(xué)設(shè)計(jì)最終都是為了滿足其能夠?qū)崿F(xiàn)特定運(yùn)動(dòng)的要求。設(shè)計(jì)的模具能否嚴(yán)格完成實(shí)現(xiàn)沖壓工藝所需的運(yùn)動(dòng),直接影響到?jīng)_壓件的品質(zhì),所以在模具設(shè)計(jì)中應(yīng)對(duì)機(jī)械運(yùn)動(dòng)進(jìn)行控制。同時(shí)為了達(dá)到產(chǎn)品形狀尺寸的要求,不能夠拘泥或局限于各種工藝基本運(yùn)動(dòng)模式中,而應(yīng)不斷發(fā)展和創(chuàng)新,在模具設(shè)計(jì)中對(duì)機(jī)械運(yùn)動(dòng)靈活運(yùn)用。
本論文是以沖壓工藝學(xué)基本理論為依據(jù),通過對(duì)各種沖壓工藝基本運(yùn)動(dòng)的分析,提出了對(duì)沖壓模具設(shè)計(jì)的要求。首先闡述沖壓過程中,機(jī)械運(yùn)動(dòng)的基本概念,然后逐項(xiàng)分析了沖裁、彎曲、拉深工藝的基本運(yùn)動(dòng)機(jī)理,指出模具設(shè)計(jì)中應(yīng)著重控制到的內(nèi)容,并介紹了在模具設(shè)計(jì)中對(duì)機(jī)械運(yùn)動(dòng)靈活運(yùn)用的方法和一些實(shí)例。最后總結(jié)了根據(jù)具體情況進(jìn)行產(chǎn)品工藝運(yùn)動(dòng)分析的方法,并強(qiáng)調(diào)在模具設(shè)計(jì)中,對(duì)機(jī)械運(yùn)動(dòng)的控制和靈活運(yùn)用對(duì)提高設(shè)計(jì)水平和保證沖壓件品質(zhì)的重要意義。
冷沖壓就是將各種不同規(guī)格的板料或坯料,利用模具和沖壓設(shè)備(壓力機(jī),又名沖床)對(duì)其施加壓力,使之產(chǎn)生變形或分離,獲得一定形狀、尺寸和性能的零件。一般生產(chǎn)都是采用立式?jīng)_床,因而決定了沖壓過程的主運(yùn)動(dòng)是上下運(yùn)動(dòng),另外,還有模具與板料和模具中各結(jié)構(gòu)件之間的各種相互運(yùn)動(dòng)。
機(jī)械運(yùn)動(dòng)可分為滑動(dòng)、轉(zhuǎn)動(dòng)和滾動(dòng)等三種基本運(yùn)動(dòng)形式,在沖壓過程中都存在,但是各種運(yùn)動(dòng)形式的特點(diǎn)不同,對(duì)沖壓的影響也各不相同。
既然沖壓過程存在如此多樣的運(yùn)動(dòng),在沖壓模具設(shè)計(jì)中就應(yīng)該對(duì)各種運(yùn)動(dòng)進(jìn)行嚴(yán)格控制,以達(dá)到模具設(shè)計(jì)的要求;同時(shí),在設(shè)計(jì)中還應(yīng)當(dāng)根據(jù)具體情況,靈活運(yùn)用各種機(jī)械運(yùn)動(dòng),以達(dá)到產(chǎn)品的要求。
沖壓過程的主運(yùn)動(dòng)是上下運(yùn)動(dòng),但是在模具中設(shè)計(jì)斜楔結(jié)構(gòu)、轉(zhuǎn)銷結(jié)構(gòu)、滾軸結(jié)構(gòu)和旋切結(jié)構(gòu)等,可以相應(yīng)把主運(yùn)動(dòng)轉(zhuǎn)化為水平運(yùn)動(dòng)、模具中的轉(zhuǎn)動(dòng)和模具中的滾動(dòng)。在模具設(shè)計(jì)中這些特殊結(jié)構(gòu)是比較復(fù)雜和困難,成本也較高,但是為了達(dá)到產(chǎn)品的形狀、尺寸要求,卻不失為一種有效的解決方法。
沖裁工藝的基本運(yùn)動(dòng)是卸料板先與板料接觸并壓牢,凸模下降至與板料接觸并繼續(xù)下降進(jìn)入凹模,凸、凹模及板料產(chǎn)生相對(duì)運(yùn)動(dòng)導(dǎo)致板料分離,然后凸、凹模分開,卸料板把工件或廢料從凸模上推落,完成沖裁運(yùn)動(dòng)。卸料板的運(yùn)動(dòng)是非常關(guān)鍵的,為了保證沖裁的質(zhì)量,必須控制卸料板的運(yùn)動(dòng),一定要讓它先于凸模與板料接觸,并且壓料力要足夠,否則沖裁件切斷面質(zhì)量差,尺寸精度低,平面度不良,甚至模具壽命減少。
按通常的方法設(shè)計(jì)落料沖孔模具,往往沖壓后工件與廢料邊難以分開。在不影響工件質(zhì)量的前提下,可以采用在凸凹模卸料板上增加一些凸出的限位塊,以使落料沖孔運(yùn)動(dòng)完成后,凹模卸料板先把工件從凹模中推出,然后凸凹模卸料板再把廢料也從凸凹模上推落,這樣一來(lái),工件與廢料也就自然分開了。?
對(duì)于一些有局部凸起的較大的沖壓件,可以在落料沖孔模的凹模卸料板上增加壓型凸模,同時(shí)施加足夠的彈簧力,以保證卸料板上壓型凸模與板料接觸時(shí)先使材料變形達(dá)到壓型目的,再繼續(xù)落料沖孔運(yùn)動(dòng),往往可以減少一個(gè)工步的模具,降低成本。?
有些沖孔模具的沖孔數(shù)量很多,需要很大沖壓力,對(duì)沖壓生產(chǎn)不利,甚至無(wú)足夠噸位的沖床,有一個(gè)簡(jiǎn)單的方法,是采用不同長(zhǎng)度的2~4批沖頭,在沖壓時(shí)讓沖孔運(yùn)動(dòng)分時(shí)進(jìn)行,可以有效地減小沖裁力。
對(duì)那些在彎曲面上有位置精度要求高的孔(例如對(duì)側(cè)彎曲上兩孔的同心度等)的沖壓件,如果先沖孔再?gòu)澢呛茈y達(dá)到孔位要求的,必須設(shè)計(jì)斜楔結(jié)構(gòu),在彎曲后再?zèng)_孔,利用水平方向的沖孔運(yùn)動(dòng)可以達(dá)到目的。對(duì)那些翻邊、拉深高度要求較嚴(yán)需要做修邊工序的,也可以采用類似的結(jié)構(gòu)設(shè)計(jì)。
彎曲工藝的基本運(yùn)動(dòng)是卸料板先與板料接觸并壓死,凸模下降至與板料接觸,并繼續(xù)下降進(jìn)入凹模,凸、凹模及板料產(chǎn)生相對(duì)運(yùn)動(dòng),導(dǎo)致板料變形折彎,然后凸、凹模分開,彎曲凹模上的頂桿(或滑塊)把彎曲邊推出,完成彎曲運(yùn)動(dòng)。卸料板及頂桿的運(yùn)動(dòng)是非常關(guān)鍵的,為了保證彎曲的質(zhì)量或生產(chǎn)效率,必須首先控制卸料板的運(yùn)動(dòng),讓它先于凸模與板料接觸,并且壓料力一定要足夠,否則彎曲件尺寸精度差,平面度不良;其次,應(yīng)確保頂桿力足夠,以使它順利地把彎曲件推出,否則彎曲件變形,生產(chǎn)效率低。對(duì)于精度要求較高的彎曲件,應(yīng)特別注意一點(diǎn),最好在彎曲運(yùn)動(dòng)中,要有一個(gè)運(yùn)動(dòng)死點(diǎn),即所有相關(guān)結(jié)構(gòu)件能夠碰死。?
有些工件彎曲形狀較奇特,或彎曲后不能按正常方式從凹模上脫落,這時(shí),往往需要用到斜楔結(jié)構(gòu)或轉(zhuǎn)銷結(jié)構(gòu),例如,采用斜楔結(jié)構(gòu),可以完成小于90度或回鉤式彎曲,采用轉(zhuǎn)銷結(jié)構(gòu)可以實(shí)現(xiàn)圓筒件一次成型。?
值得一提的是,對(duì)于有些外殼件,如電腦軟驅(qū)外殼,因其彎曲邊較長(zhǎng),彎頭與板料間的滑動(dòng),在彎曲時(shí),很容易擦出毛屑,材料鍍鋅層脫落,頻繁拋光彎曲沖頭效果也不理想。通常的做法是把彎曲沖頭鍍鈦,提高其光潔度和耐磨性;或者在彎曲沖頭R角處嵌入滾軸,把彎頭與板料的彎曲滑動(dòng)轉(zhuǎn)化為滾動(dòng),由于滾動(dòng)比滑動(dòng)的摩擦力小得多,所以不容易擦傷工件。
Stamping mould design of mechanical motion control and use
In the stamping process, mechanical motion throughout. All kinds of the realization of the stamping process has its basic movement mechanism, this movement is closely related with the mould, all kinds of die structure design and mechanical design is finally all in order to meet the specific requirements of the movement to realize. The design of the mould can finish stamping process strictly to realize the movement, directly affects the quality of the stamping, so in the mold design of mechanical movement to control. In order to achieve the requirements of the product shape and size, can't get bogged down or confined to various process basic sports mode, and should constantly development and innovation, in the mold design of flexible use of mechanical motion. Abstract: in the stamping process, mechanical motion throughout. All kinds of the realization of the stamping process has its basic movement mechanism, this movement is closely related with the mould, all kinds of die structure design and mechanical design is finally all in order to meet the specific requirements of the movement to realize. The design of the mould can finish stamping process strictly to realize the movement, directly affects the quality of the stamping, so in the mold design of mechanical movement to control. In order to achieve the requirements of the product shape and size, can't get bogged down or confined to various process basic sports mode, and should constantly development and innovation, in the mold design of flexible use of mechanical motion.
This paper is based on the basic theory of stamping technology, through various stamping process basic motion analysis, proposed to the stamping mould design requirements. The paper stamping process, mechanical motion of the basic concepts, and then analyzed, item by item, cutting, bending, deep drawing technology, and points out that the basic motion mechanism mold design of should focus on the content of the control to, and introduces in the mold design of flexible use of mechanical motion of the methods and some examples. The conclusion according to the specific situation of product craft movement analysis method, and emphasized in the mold design, mechanical movement to control and flexible to improve design level by stamping and guarantee the quality of the important significance.
Cold stamping is of different specifications will be in the process of sheet metal or blank mould and stamping equipment, use (press, another name to pressure the punch), the deformation or separation, access to certain shape, size and performance of the parts. General production is the vertical punch, and decided the main movement of stamping process is up and down movement, in addition, there is the sheet metal mold and die in the structure of all kinds of mutual movement between.
Mechanical motion can be divided into sliding, the rotation and rolling, three basic forms of exercise in stamping process, there are various forms of exercise, but the different characteristics, the influence of the stamping is different.
Since stamping process is so diverse movement and in stamping mould design for all kinds of sports should be strict control, in order to achieve the mould design requirements; At the same time, in a design should also according to the specific circumstances, make use of various mechanical motion, in order to achieve the requirements of the product.
Stamping process is main movement up and down movement, but in the mold of inclined wedge design structure, structure, structure and presenting roller rotary cutting structure etc, can the corresponding main movement into level sports, of die and mould rotation of the scroll. In the mold design of these special structure is more complex and difficult, costs are high, but in order to achieve a product's shape, size requirement, but is a good solution.
Cutting craft basic motion is unloading board first contact and sheet metal press a prison, the punch down to the sheet metal contact and continue to fall into the concave die, convex, concave die and relative motion sheet metal sheet to separate, then convex, concave die separate, unloading board the piece or waste from the punch, and complete the lagging on cutting movement. The movement of unloading board is critical, in order to ensure the quality of the cutting, must control the movement of unloading board, make it before the punch and sheet metal contact, and the material force should be enough, or cutting a cut area poor quality, low dimensional accuracy, flatness bad, and even die life is reduced.
According to the common method of design blanking punching die, often after stamping workpiece and waste to separate edge. No impact on the premise of workpiece quality, can use in die and punch unloading board adding some protruding set blocks, in order to make blanking punching movement, concave die after the completion of the unloading board first the piece out from the concave die, and die and punch unloading board again from the waste die and punch. So, lagging the workpiece and waste natural separated.
For some of the larger local convex stamping, can be in blanking punching die of concave die unloading board type pressure of the punch, and at the same time put enough spring force, in order to ensure that the unloading board pressed the punch and sheet metal contact material deformation are first to pressed purpose, continue to blanking punching, often can reduce sports a work of mold, reduce cost step.
Some punching mould punching number, need very blunt, stamping production negative pressure, and even without enough tonnage of punch, has a simple method, it is to use different lengths of 2 ~ 4 batch of punch in stamping, let punching movement points, and can be effectively reduced cutting force.
For those in bending surface position precision of the high demand of the hole (such as the two aperture concentricity bending, etc.) of the stamping, if the first bend is difficult to meet again punch a hole requirements, must design the structure of the bending, wedge again after the utilization level of direction, punching punching movement can achieve a goal. For those who turn over the side, deep drawing height stricter requirements need to do trimming process, also can with similar structure design.
Bending process basic motion is unloading board first and sheet metal contact and killed, the punch down to the sheet metal contact, and continue to fall into the concave die, convex, concave die and relative motion in sheet metal, sheet metal bending deformation, and then convex, concave die bending concave die apart, on top of the stem (or the slider) to launch, complete edge bending bending movement. Unloading board and top of the stem movement is a key, in order to guarantee the quality of the bending or production efficiency, must first control the movement of unloading board, let it before the punch and sheet metal contact, and the material force must be enough, or bend a size accuracy is poor, poor plane degree; Second, shall ensure that top stem force enough, to make it successfully launched the bending parts, or bend a deformation, the production efficiency is low. For higher accuracy bending part, should pay special attention to a little, best in bending movement, want to have a movement, that all relevant parts dead spots can touch death.
Some of the more exotic, or bend shape after bending according to normal way not from concave die off, at this time, often need to use the wedge structure or structures, such as by presenting, inclined wedge structure, can complete less than 90 degrees or back to hook type bending, presenting the structure can realize a forming a cylinder.
Be worth what carry is, for some shell parts, such as computer floppy drive enclosure, because of its bending side is longer, elbow and between the sheet metal bending, sliding, in very easy to wipe out soft flocks, materials galvanized layer falls off, frequent polishing curved punch effect is not ideal. It is usually the bending the punch of titanium coating, and improve the finish and wear resistance; Or in bending the punch R Angle place the elbow and embedded roller, sheet metal bending sliding into rolling, because than sliding friction small roll, so not easy scratches workpiece.