Superplasticforming bakelite hand wheel and die design

手轮是摩」旧挺尾机上的二个主要零件。">Tooth clutch fork and hand wheel are the two main parts of Morocco " very old tail machine. They originally die casting, because when the solidification easy to form columnar grains , the performance does not meet the requirements. If using plastic forming , to improve their performance, increase service life , but the more complex shape parts ( fork 6 l.85 mm radius as small hemisphere , except for eight dimensions have tolerances , the other dimensions are freely tolerance ) , and QA I 10 a 3 a 1.5 and QA1 9 -4 aluminum bronze and high yield strength , if used general forging method ( such as hot forging , cold and warm extrusion , etc. ) would be difficult molding , the mold material " thermal processing " S / 19 and that the design requirements are high, forming force as well.
        Therefore, we superplasticity and superplastic forming process bakelite hand wheel is studied . Practice shows , super plastic forming method Forming aluminum bronze fork and hand wheel is an ideal plastic processing methods. Mechanical properties are shown in Table 2 ) by superplastic pretreatment superplastic tensile tests conducted to obtain weapons flow stress elongation Wu Bu Bu m ( strain rate sensitivity refers to as the temperature T and BU . and strain rate .
Second, the analog parts superplastic forming to more accurately estimate the experimental Superplasticforming fork , hand wheel deformation resistance , materials flow and filling of determining forming lubricants , mold design bakelite hand wheel to provide a reliable basis , Superplasticforming fork with the same hand wheel design a simulation piece , its projected area S and fork , roughly equal to the handwheel ' simulated superplastic forming part of the working conditions .
        1 Number of superplastic forming process now Superplasticforming process parameters are: forming temperature , forming speed and lubricants superplastic forming temperature can be controlled within the range of the instrument soil 10 ℃, strain rate . Usually by controlling the pressure indirectly controlled motorized beam velocity v (due proportional to v.) Circumference , accounting , are more appropriate ( 2 ) moving beam velocity v:.. Superplastic materials generally more sensitive to deformation rate will = k: m ) .
The two -way superplastic tensile alloys ( uniaxial stress state survey experiment , the initial strain rate of 10 a , a 0.7 5 x 10 a , m in a ' time change , little change in the flow stress ( in an order of magnitude inside ) , and simulation for fork , super plastic forming handwheel is under intense pressure to perform three stress will inevitably lead to increased deformation resistance . analog parts forming force P with P =. ·, be estimated , take . = 10 kg / mm Z, s = 49 1 mm 2, the forming force is about 5t. optional 10 0t plastics hydraulic machines, enough to meet the shape requirements, and a greater tonnage of reserves. tentative value V l a l . sm m / m within in range ( 3 ) lubricant : super plastic forming lubricant for forming, forming part quality , mold , oxidation has an important impact on bakelite hand wheel test a variety of lubricants, effect. not ideal lubricants such as graphite at high temperature burning severely affect lubrication ; glass and graphite mold after forming a strong resistance ; greater pure glass powder lubricant resistance , easy to clean , often caused by high temperatures can not be out of the mold . ring emblem crude test and simulation experiments forming , 2 # lubricant ( market purchase ) to good effect. forming the analog parts, clear edges , forming a force of about 6 8t, · forming speed V at 1.4 a 1.sm m / m in. insulation 10m in .2. simulate analog parts mold mold material work better part of the selection of the high-temperature strength of superalloys GH 36, mold base and other parts of the non-working part of the selected Ic r 13. Third, call fork, hand wheel superplastic forming die design 1.
Figure develop forging forming through holes in the volume is not easy to achieve , not forming, machining left to follow in order to avoid the punch , die in direct contact , reducing cutting accuracy than in forging the upper left block , skin , used to adjust the blanks sizes, after forming the car cut off .2 . punch and die design and choice of forging billet mold , the punch and die mold structure is reasonable relationship to the level of costs , ease of processing , and the success or failure of the forming mold longevity , etc. the problem with fork , for example, to discuss its structural design of the mold (l) fork hemisphere R 1.8 5 in the closed die forming :. A. adoption. Upsetting the first blank 13 , the forward and reverse extrusion ( Figure 6 ) . Blank positioning accuracy of this method , but the material elongated , increasing the length of the guide die .
        Forming complete, easy to produce folding metal reflux for R 1.85 hemisphere forming extremely unfavorable . B. adoption. Forming cylindrical blank 27 ( Figure 7 ) , not only to avoid the A . Disadvantages elongate blank 13 , while also accurately positioned , and the casting may have a reasonable flow line , to improve the impact properties of the parts is very useful. POW ) R 1.85 hemisphere shaped punch in closed , as shown in Figure 8 such structure is undesirable. because the punch of " blade " bakelite hand wheel exist , low die life. From the above analysis , the use of the structure R l.85 hemisphere forming die in the blank of 27 cylindrical ideal . '3 by other nodes tear meter (l) of the mold -oriented : the use of die -oriented mold structure can be simplified , eliminating the need for guide pins and bushings convex and concave mold with the same kind of manufacturing materials , can effectively prevent mold due to the material caused by different coefficients of expansion " jamming " phenomenon of the die mold structure plus R 3 rounded as shown in Figure 9 ( 2 ) limit : due to the use of closed molding method , when the material to fill the mold cavity , the deformation resistance will increase rapidly. thereby forming force can be controlled by controlling the amount of depression , to limit the purpose .
4 chess fork materials and processing methods , the hand wheel is formed at higher temperatures , the working portion of the parts to be heat-resistant alloys due to these two alloys have very low flow stress in the superplastic state ( Forming Simulation the average principal stress parts : QAl lo a 3 a 1.5 and a 4 QA1 9 respectively 12 kgr / mm Z and 1 6 kg r / mm Z or so ) , so the lower mold material strength requirements under the existing circumstances chosen . Cr2 0 N i24 of material si 4T i this alloy has good oxidation resistance and high temperature strength but not ideal , by 1050 soil 20 ℃ x 4 h, air cooling , the hardness is still low old Xu Liang V 14 1).
        A 3 other parts are made of steel . Punch processing is simple , with EDM die after by liquid sandblasting, finish up 6.5 Dimensions computing QA l Bu 3 a 1.5 and QA 19 -4 measured linear expansion coefficient is the maximum at 70 ℃ , but decreased than 7 0 ℃ measured data shown in Table 4 . Since the linear expansion coefficient of the mold slightly before forging ' and cooling , the design time can be taken as 70 ℃ design calculations basis . r2 0Ni 24 si 4T i is the new developed materials , data is not readily available . superalloys similar grades of analog design data . investigation ZCr 2 0Mn gN provided S of N, 70 0 ℃ , the linear expansion coefficient of 18.7 x . lo lure / ℃ calculated as follows (omitting the elastic deformation ) : na l ten a tT) = L two ( one of which ten gas persuade forging plant design size L ; L ' corresponding mold size ; af- forging linear expansion coefficient of the material ; , a linear expansion coefficient of the mold material ;. T -temperature shrinkage of unit size = Lm / L, = (l + a tT) / (1 + ao T) a, bakelite hand wheel takes two linear expansion coefficient of aluminum bronze average of 19 .0 x 10 a / ℃; a two take a 8,7 fire 1 0, / ℃, T takes 70 0 ℃, calculated and = 1.0 0021 .
        Since forging dimensional changes caused by thermal expansion of the material is very small , the size of the tip of the fork and bakelite hand wheel is not high , its impact can be omitted . Fourth, fork , hand wheel superplastic forming process parameters to consider pulling superplastic stretch test and simulation results superplastic forming pieces , fork , super plastic forming process parameters determine the handwheel in Table 5 . Silicon carbide furnace heating using two semicircular watts each Zk w embedding a resistance wire, while the upper and lower heating plates are simultaneously heated , the mold can effectively reduce heat loss using a nickel- chromium- nickel-aluminum thermocouple temperature , equipped with U J32a portable DC potentiometer , temperature control with auto-transformer Figure 10 is a moving beam weight ( about 0.90 forging the blank to complete the initial shaping of the hand wheel according dream figure, to 7 ( counterclockwise direction) by successively feeding blank 2. 5, 3, 4,6,8, 12 m in the resultant molded member is loaded only on the 7th member resultant Figure 1 is loaded by the weight of the movable yoke resultant recording beam curve curve is w EY lo -type strain displacement sensor , Y 6A -3 -type dynamic resistance strain gauge , by xy recorder function measured . forming 1o m in the future , the displacement is basically stable, but not the final accurate forming, need to be loaded , about 5 to st. handwheel forming , forging fork shown in Figure 10 .
        Real Russian side parts are to meet the technical requirements. Five , super plastic forming experimental data processing and analysis of measurement results of seven forgings ( which QAl lo a 3 a 1.5 forging three , Q A1 9 a 4 forging four ) , which at the same site are 24 .9 2 mm, and the corresponding parts of the die cavity size is 24 .9 8m m, with part size as a benchmark, while seeking its magnification and die size ; = 24.98 / 2 = 1.0 24 24.9 calculates the difference compared with the previous analogy an order of magnitude . Figure 13 is a graph of 10 forks fit a travel time curve which RZ value parameter to characterize the degree of fit pots , RZ closer l, the better the fit , which is the principle of least squares , computer programming ( program slightly ) , drawn by the computer which is a good fit RZ =. .9 46 , corresponding to equation Y = 2. 782 x 03.
Sides of the equation derivation time t , to obtain the pressure beam maneuvering speed ( where x = t), v two dy / dx = 0.8 62 x A , and then obtaining the derivative of the acceleration of t a = dy / dT = a o. 5 9 5 x a '· the computer draw v, a curve as shown in Figure 14 when x = 3 a 4, that the weight of forming three or four minutes later , the acceleration a value close to zero value, which is the basic speed V a stable , bakelite hand wheel this time v value of about 0 .4 mm / m in the left and right , which shows a certain load shaping , just long enough to complete the forging forming , which has important practical significance as can be with a certain load ( ie, small -tonnage presses ) to a small forming speed , you can complete the superplastic forming large forgings . fork part shape is more complex, with some representation this method is widely used in instrumentation, other aluminum bronze chemical, aviation, marine, oil (Q Al lo a 3- LS, QA 19 -4 ) pieces , can be a shape. forming force than other plastic processing lower. forming a forging of the experiment 3 a 1 ​​Zm in, productivity is low.
        In actual production , according to the complexity of the parts , plastic materials under normal four reserves in the electron microscope lenses , diffraction mode selection, lens defocus , bakelite hand wheel to make things mirror plane located above the diffraction pattern , not relative to the image plane diffraction pattern rotation , this time comparing the transmission diffraction spot image and the selection of the image selection can be determined whether there is between 180 ' is rotated , when they match , there is no 180 ' is rotated, otherwise 180 ' is rotated in the presence of stainless steel '3 twinning marked at a magnification of 730 and 15,000 times the rotational case 730 times the defocused image is consistent with SAD, 180 do not exist . rotation, and 1500 times , both the contrary, the presence of rotation. 's size, equipment, energy storage size , with large blank preheat the oven to a high forming speed forming, shaping can shorten the time after study shows that aid fork parts forming time can be shortened to 1m in, then forming force about 40 ~ 60 t.