【正文】 。即：，其中，查《機(jī)床夾具設(shè)計(jì)手冊(cè)》表121得：；；；；；；，所以=。==。繪圖時(shí)先用雙點(diǎn)劃線（細(xì)線）繪出工件，然后在各個(gè)定位面繪制出定位元件和夾緊機(jī)構(gòu)，就形成了夾具體。2 結(jié)構(gòu)設(shè)計(jì)工作部位本例按同時(shí)檢驗(yàn)設(shè)計(jì)。（二）工作部位尺寸計(jì)算1 量規(guī)公差 根據(jù)，分別由表43和表44序號(hào)查得 2 按公式計(jì)算位置量規(guī)工作部分尺寸 （由工作者確定，現(xiàn)若取為14） (71) 圖72 主體結(jié)構(gòu)圖8夾具設(shè)計(jì)在機(jī)械制造中，為完成需要的加工工序、裝配工序及檢驗(yàn)工序等，使用著大量的夾具。 夾具設(shè)計(jì)的基礎(chǔ)理論一個(gè)好的機(jī)床夾具，首先要保證能加工出合格的產(chǎn)品。因?yàn)榧庸け砻媸怯汕邢鞯毒吆蜋C(jī)床的綜合運(yùn)動(dòng)所造成，所以在加工時(shí)，必須使加工件上的規(guī)定表面(線、點(diǎn))對(duì)刀具和機(jī)床保持正確的位置才能加工出合格的產(chǎn)品。當(dāng)物體的六個(gè)自由度被完全限制后，該物體在空間的位置也就完全確定了，所以定位就是限制自由度；在夾具中限制加工件的自由度在夾具中，使加工件的規(guī)定表面與定位元件接觸，就能限制自由度。 夾緊原理 在生產(chǎn)實(shí)踐中，盡管定位方式是合理的，但由于夾緊狀態(tài)不良(即夾緊力的大小、方向、作用點(diǎn)和支承的位置選擇不當(dāng))可能出現(xiàn)如下問題：①加工件飛出夾具，打壞刀具，造成安全事故；②加工出來的位置尺寸不準(zhǔn)確；③ 加工表面產(chǎn)生形位公差(如不平度、不垂直度)；① 加工表面粗糙度高等。所以在考慮定位方案及設(shè)置定位支承時(shí)，應(yīng)盡可能使支承反力與重力不構(gòu)成力偶，使加工件重心位于支承范圍內(nèi)。所以在制定夾緊方案時(shí)，對(duì)于剛性較差的加工件，應(yīng)盡可能避免產(chǎn)生或應(yīng)盡可能減小由夾緊力產(chǎn)生的彎曲力矩。所以，在制定夾緊方案時(shí)，切削力最好由支承反力平衡，而盡可能避免用夾緊力及由夾緊力產(chǎn)生的摩擦力平衡。20世紀(jì)80年代以來，將計(jì)算機(jī)技術(shù)應(yīng)用到夾具設(shè)計(jì)中一直是機(jī)械領(lǐng)域研究的課題之一。這些都是基于二維平臺(tái)開發(fā)的。首先根據(jù)工件特征、工序信息及夾具信息，調(diào)用有關(guān)的程序和數(shù)據(jù)協(xié)助技術(shù)人員來完成夾具的定位方案、導(dǎo)向方案、夾緊方案的設(shè)計(jì)，并通過人機(jī)交互的方式完成各功能元件和部件的選擇和設(shè)計(jì)。如何充分利用已有夾具信息成為CAFD系統(tǒng)的關(guān)鍵環(huán)節(jié)。同時(shí)，以計(jì)算機(jī)輔助夾具設(shè)計(jì)系統(tǒng)為基礎(chǔ)的夾具信息系統(tǒng)是CIMS中信息集成的一個(gè)重要環(huán)節(jié)。因此對(duì)夾具設(shè)計(jì)方法提出了更高的要求，它不僅能將CAD/CAM系統(tǒng)有效地聯(lián)接起來，同時(shí)應(yīng)能適用于各種形狀的工件。另一方面，計(jì)算機(jī)技術(shù)的發(fā)展為夾具設(shè)計(jì)提供了有利的工具。歸納目前CAFD系統(tǒng)的研究方向主要包括以下幾個(gè)方面：(1)集成化。集成化是CAFD系統(tǒng)發(fā)展的必然方向，是企業(yè)信息集成的必然要求。(3)并行化。在對(duì)半軸的工藝性進(jìn)行了詳細(xì)的分析后，設(shè)計(jì)出了加工的工藝過程，根據(jù)加工要求設(shè)計(jì)專用夾具設(shè)計(jì)，一付是用來車削半軸的外圓，一付是用來鉆削半軸圓盤上均勻分布的小孔，在設(shè)計(jì)中注意的夾具的經(jīng)濟(jì)性和使用性，盡量降低加工時(shí)的成本，減少工人的勞動(dòng)強(qiáng)度，除此還進(jìn)行了組合量具的設(shè)計(jì)，用來檢查6個(gè)均勻分布的小孔的位置度公差。s muscular energy acting on the service brake control and the requirements of paragraph . are met.. certain parts, such as the pedal and its bearing, the master cylinder and its piston or pistons (hydraulic systems),the control valve (hydraulic and/or pneumatic systems), the linkage between the pedal and the master cylinder or the control valve,the brake cylinders and their pistons(hydraulic and/or pneumatic systems), and the leverandcam assemblies of brakes, shall not be regarded as liable to breakage if they are amply dimensioned,are readily accessible for maintenance,and exhibit safety features at least equal to those prescribed for other essential ponents(such as the steering linkage)of the such part as aforesaid whose failure would make it impossible to brake the vehicle with a degree of effectiveness at least equal to that prescribed for secondary braking must be made of metal or ofa material with equivalent characteristics and must no tunder notable distortion in normal operation of the braking systems.. Where there are separate controls for the service braking system and the secondary braking system, simultaneous actuation of the two controls must not render both the service braking system and the secondary braking system inoperative, either when both braking systems are in good working order or when one of them is faulty.. The service braking system must,whether or not it is bined with the secondary braking system, be such that in the event of failure in a part of its transmission a sufficient number of wheels are still braked by actuation of the service brake control。s intentions.. The service,secondary and parking braking systems must act on braking surfaces connected to the wheels through ponents of adequate strength. Where braking torque for a particular axle or axles is provided by both a friction braking system and an electrical regenerative braking system of category B,disconnection of the latter source is permitted, providing that the friction braking source remains permanently connected and able to provide the pensation referred to in paragraph . However in the case of short disconnection transients, inplete pensation is accepted, but within 1 s, this pensation shall have attained at least 75 per cent of its final value. Nevertheless, in all cases the permanently connected friction braking source shall ensure that both the service an secondary braking systems continue to operat with the prescribed degree of of the braking surfaces of the parking braking system shall be permitted only on condition that the disconnection is controlled exclusively by the driver from his driving seat,by a system incapable of being brought into action by a leak.. Wear of the brakes must be capable of being easily taken up by means of a system of manual or automatic addition,the control and the ponents of the transmission and of the brakes must possess a reserve oftravel and, if necessary, suitable means of pensation such that, when the brakes bee heated, orthebrake liningshave reached a certain degree of wear,effective braking is ensured without immediate adjustment being necessary.. Wear adjustment shall be automatic for the service brakes. However, he fitting of automatic brake adjustment devices is optional for off road vehicles of categories N2 and N3 and for the rear brakes of vehicles of categories M1 and equipped with automatic brake adjustment devices shall,after heating followed by cooling,be capable of free running as defined in paragraph . of annex 4 following the TypeI test also defined in that annex.. Checking the wear of the service brake friction ponents. It shall be possible to easily check this wear on service brake linings from the outside or underside of the vehicle utilizing only the tools or equipment normally supplied with the vehicle, for instance by the provision of appropriate inspection holes or by some other means. Alternatively,acoustic or optical devices warning the driver at his driving position when lining replacement is necessary are yellow warning signal specified in . below may be used as the optical warning signal.. Assessment of the wear condition of the friction surfaces of brake discs or drums may only be performed by direct measurement of the actual ponents, which may necessitate some level of , at the time of type approval, the vehicle manufacturer shall define the following: (a)The method by which wear of the friction surfaces of drums and discs may be assessed, including the level of disassembly required and tool