Existing state of affairs of development of miniature machining technology and trend reach its key ability

35 ～ 0.

4) Ⅱ of σ B kind [τ ] = (0.

4 ～ 0.

47) Ⅲ of σ B kind [τ ] = (0.

5 ～ 0.

55) τ of σ B [] = (0.

44 ～ 0.

532) σ B[τ ] = (0.

50 ～ 0.

625) σ B[τ ] = (0.

62 ～ 0.

731) Ⅰ of bedspring of σ B drawing kind = [τ ] (0.

28 ～ 0.

32) Ⅱ of σ B kind = [τ ] (0.

32 ～ 0.

38) Ⅲ of σ B kind = [τ ] (0.

40 ～ 0.

44) τ of σ B [] = (0.

35 ～ 0.

425) σ B[τ ] = (0.

40 ～ 0.

505) σ B[τ ] = (0.

50 ～ 0.

585) the working limit before σ B turns round bedspring to twist processing by force curves Ⅱ of stress σ F kind [τ ] = 0.

Ⅲ of 625 σ B kind [τ ] = 0.

The limit that can reach after prestressing of 80 σ B curves τ of stress σ F[] = (0.

78 ～ 0.

83) σ B[τ ] = (1.

00 ～ 1.

06) σ B notes: (1) Ⅰ kind load (106 above) ; Ⅱ kind load (103 ～ 105) ; Ⅲ kind load (103 the following) (2) coerce (pull, twist) what can achieve after processing is allowable stress is to press coerce (pull, twist) before processing allowable 1 of stress.

25 ～ 1.

33 times computation gets. Can make through prestressing bedspring increases carrying capacity at a draught 25% ～ 33% , for this technical staff that to just contacting machinery the spare parts designs, it is one has very absorbing data really. But, through the author's practice and analysis, think: Through coercing (pull, twist) the carrying capacity that processing will come raise spring is conditional. Because be in prestressing process, arise bedspring material surface layer beneficial as retrorse as working stress leftover stress only, ability achieves coerced result, and be in only coerce (pull, twist) when, make the leftover stress that bedspring material produces namely plasticity is out of shape bigger, the stretch limit of bedspring material rises more greatly. But the stretch limit of every kinds of material is to have certain limit, once exceed this limit, material can produce plasticity to be out of shape not only, and meeting " succumb completely " be out of shape, a lot of bedspring are in coerce (pull) 0 to material.

5 σ B already " succumb completely " be out of shape. All sorts of data yield limiting value also has difference, succumb the ability after limiting value can pass intensity checking computations and test only is affirmatory. Additional, coerce (pull, twist) the appearance structure of the effect of processing and bedspring, characteristic, and the technique of prestressing has close relationship. the appearance structure with respect to bedspring, convolute than big or helix promotes role small (compress bedspring) the carrying capacity that raise it impossibly through prestressing, convolute more or less can achieve a goal after all than promoting role with helix, need to decide through coercing design and experiment ability. So, be not is simple merely press spring, pull or twist, can increase carrying capacity at a draught how many of how many. The analysis on put together, of bedspring prestressing press stress τ Qy or pressure PQy should satisfy the following formula to ask above all: ≥ of S of τ of ＞ of D3 of π of τ Qy = 8DPQy / 0.

5 at the same time, when ＞ of B of σ of τ Qy / 0.

8 when, can make material is achieved succumb the limit, bedspring appears permanent be out of shape, make load decreases instead. Because of this prestressing press B of σ of stress τ Qy / to must be in 0.

5 ～ 0.

Inside 8 limits. From above can see in form: Unless be tall stress bedspring, general compression, drawing and turn round bedspring to be not had coerce (pull, twist) essential condition, but can pass pair of bedspring to undertake " prefab tall " craft will create a condition. For example: To compressing bedspring is mixed turn round bedspring, can pass what to it obligate coerces " prefab tall " and " prefab horn " will achieve two goals: It is to make bedspring material sectional surface layer can produce leftover stress " reduce an amount " and " turn round a quantity " ; The 2 high dimension that are the bedspring after passing prestressing or angle as it happens accord with the requirement of the design. To drawing bedspring the first purpose comes true not easily. Be opposite before according to the analysis of above and author of effect of prestressing of frustum form bedspring discuss, get the opinion of bedspring prestressing is is opposite: 1, when considering to want to make prestressing to bedspring, should undertake coercive designing to bedspring first, do prestressing in order to decide whether this bedspring suits. 2, the compression that have prestressing requirement and suffers tall stress bedspring, turn round bedspring to wait, after passing prestressing, mechanical function can get clear improvement. 3, have the drawing spring that pulling force asks first, when pulling processing by force tensile meeting decreases to disappear even first, this kind of bedspring cannot be done pull processing by force. And without the drawing bedspring that pulling force asks first, increase carrying capacity not easily through pulling processing by force. 4, high temperature (more than + 60 ℃ ) the spring that reachs the job below burn-in condition makes prestressing, can have the effect of stable dimension only, cannot increase carrying capacity. 5, the carrying capacity that increases frustum form bedspring through coming with the method of prestressing cannot be being taken actually, can conclude with this piece: To all sorts of changing the bedspring of stiffness, the method that is unwell and operable prestressing will increase its carrying capacity. 2, be opposite to satisfy about electropolishing processing the mechanical function of the stretch spare parts of requirement nicety, a few document put forward: "The spring that can agree gold, copper alloy and stainless steel silk to make to using nicety undertakes chemical perhaps polish handles electropolishing, reduce material surface layer with minim, will achieve the dimension of need and character. " after the author passes practice, think, using electropolishing is the size that can reduce bedspring surface layer, this is a few righter compress it is bedspring, OK to play reed and moire pipe use appropriately, but to drawing, turn round wait for the bedspring that does not have clearance, unwell and operable electropolishing will reduce its mechanical function. Because, the electric current of electropolishing and fluid of its report interpose (contain vitriolic, nitric acid to wait) inside cutty time (the time of polishing is average 8 seconds of 2 ～ ) cannot even ground passes the aperture between bedspring circle and circle, after be being handled through electropolishing so pull, the sectional diameter of the material that twist reed became the entity side inhomogenous, irregular much arris, this asks that this cannot be taken for taller bedspring to precision. Consider the influence of bedspring function to set out from electropolishing, it is unfavorable go with overmuch time electropolishing, because be in,the time of acerbity solution grows too, be very existence to the influence of bedspring intensity, and it is harmful. Next, the solution operating period of electropolishing is inferior, craft parameter change is big, the ability after every batches of bedspring need to pass a test is affirmatory, from economically the consideration also raised cost. At present the spring steel silk of all sorts of diameter norms has all sorts of names supply, basically can satisfy the mechanical function of all sorts of accurate demand spring. The place on put together narrates pair of drawing bedspring and turn round bedspring, want to reduce its minim size through electropolishing, in order to achieve the character of need, cannot take. Also put in same question to chemical polish. 3, the design about frustum form bedspring after 1982, the design calculation method that introduced to wait for helix to rise spring of horny frustum form in all sorts of machinist Cheng manual that our country publishs, mention the corkscrewed yarn that waits for helix to rise place of bedspring of horny frustum form to form among them, what go up in as perpendicular as photograph of bedspring center line bearing face is umbriferous it is pair of maths spiral, namely: In of ＝ of M of θ of R ＝ R1em (R2-R1) / 2 π but, be out of shape in what introduce this kind of spring actually and when stress computation and its geometry dimension, mix it again wait for confuse sth with sth else of bedspring of pitch frustum form. Design and make what this gives those who have precision demand to wait for helix to rise spring of horny frustum form bring difficulty. The author needs because of the job, once derivation crosses the design calculation method that waits for helix to rise spring of horny frustum form, once also had consulted abroad concerns the design calculation method that waits for helix to rise spring of horny frustum form, among them before the computational formula of Russia is completely correct, accurate. Additional, the design computation formula that waits for bedspring of pitch frustum form also is put in a few problems. Will put forward to discuss in special implied meaning henceforth. Calculate in the design of frustum form bedspring on this problem, to " mechanical design manual " the validity of manual of directiveness of design of this China mechanical spare parts and accuracy, whether to have some of small regret. Afore-mentioned point of views that language author offers after for the technical personnel to be engaged in bedspring technically, it is negligible probably. But, " mechanical design manual " the object is domestic and international broad the Scientists and Technologists that is engaged in machinist Cheng is designed and be being made, " mechanical design manual " be have directiveness, authority and classical literature originally, the content such as the viewpoint method in manual and formula, must be close and accurate, accord with production actual. It is difficult to can give use unit and belt of the member that make servantchoose a person for a job to go otherwise with the trouble. Finally, the design of our country bedspring already involved a lot of phyletic bedspring with production standard, but the design of frustum form bedspring is returned with production standard is a blank. Frustum form bedspring makes industry wait to be in in the aviation of our country, spaceflight and car application. Whether can you establish the standard of bedspring of form of a frustum in opportune opportune moment? CNC Milling CNC Machining