注塑模具畢業(yè)設(shè)計(jì)外文翻譯--立體光照成型的注塑模具工藝的綜合模擬（英文）

1、DOI 10.1007/s00170-004-2327-9OR I GI NAL AR T I C LEInt J Adv Manuf Technol (2006) 28: 53–60Huamin Zhou · Dequn LiIntegrated simulation of the injection molding process with stereolithography moldsReceived: 5 March

2、2004 / Accepted: 5 July 2004 / Published online: 6 April 2005 © Springer-Verlag London Limited 2005Abstract Functional parts are needed for design verificationtesting, field trials, customer evaluation, and producti

3、on plan- ning. By eliminating multiple steps, the creation of the injec- tion mold directly by a rapid prototyping (RP) process holds the best promise of reducing the time and cost needed to mold low-volume quantities of

4、 parts. The potential of this integra- tion of injection molding with RP has been demonstrated many times. What is missing is the fundamental understanding of how the modifications to the mold material and RP manufacturi

5、ng process impact both the mold design and the injection mold- ing process. In addition, numerical simulation techniques have now become helpful tools of mold designers and process engi- neers for traditional injection m

6、olding. But all current simulation packages for conventional injection molding are no longer ap- plicable to this new type of injection molds, mainly because the property of the mold material changes greatly. In this pap

7、er, an integrated approach to accomplish a numerical simulation of in- jection molding into rapid-prototyped molds is established and a corresponding simulation system is developed. Comparisons with experimental results

8、are employed for verification, which show that the present scheme is well suited to handle RP fabri- cated stereolithography (SL) molds.Keywords Injection molding · Numerical simulation · Rapid prototyping1 Int

9、roductionIn injection molding, the polymer melt at high temperature is injected into the mold under high pressure [1]. Thus, the mold material needs to have thermal and mechanical properties capa- ble of withstanding the

10、 temperatures and pressures of the mold- ing cycle. The focus of many studies has been to create theH. Zhou (u) · D. Li State Key Lab of Mold u, v are the average whole-gap thick- nesses; and η, ρ, CP(T), K(T) repr

11、esent viscosity, density, spe- cific heat and thermal conductivity of polymer melt, respectively.In addition, boundary conditions in the gap-wise directioncan be defined as:u = w = v = 0, T = TW at z = b (5)?u?z = 0 = ?v

12、?z , ?T?z = 0, w = 0 at z = 0 (6)where TW is the constant wall temperature (shown in Fig. 2a).Combining Eqs. 1–4 with Eqs. 5–6, it follows that the distri-butions of the u, v, T, P at z coordinates should be symmetrical,

13、 with the mirror axis being z = 0, and consequently the u, v av- eraged in half-gap thickness is equal to that averaged in whole- gap thickness. Based on this characteristic, we can divide the whole cavity into two equal

14、 parts in the gap-wise direction, as described by Part I and Part II in Fig. 2b. At the same time, triangular finite elements are generated in the surface(s) of the cavity (at z = 0 in Fig. 2b), instead of the middle-pla

15、ne (at z = 0 in Fig. 2a). Accordingly, finite-difference increments in the gap- wise direction are employed only in the inside of the surface(s) (wall to middle/center-line), which, in Fig. 2b, means from z = 0 to z = b.

16、 This is single-sided instead of two-sided with respect to the middle-plane (i.e. from the middle-line to two walls). In add- ition, the coordinate system is changed from Fig. 2a to Fig. 2b to alter the finite-element/fi

17、nite-difference scheme, as shown in Fig. 2b. With the above adjustment, governing equations are still Eqs. 1–4. However, the original boundary conditions in the gap- wise direction are rewritten as:u = w = v = 0, T = TW

18、at z = 0 (7)?u?z = 0 = ?v?z , ?T?z = 0, w = 0 at z = b (8)Meanwhile, additional boundary conditions must be employed at z = b in order to keep the flows at the juncture of the two parts at the same section coordinate [7]

19、:uI = uII; vI = vII; TI = TII; PI = PII at z = b (9)Cm ? I = Cm ? II (10)where subscripts I, II represent the parameters of Part I and Part II, respectively, and Cm-I and Cm-II indicate the moving freeFig. 2a,b. Illustra

20、tive of bound- ary conditions in the gap-wise direction a of the middle-plane model b of the surface modelmelt-fronts of the surfaces of the divided two parts in the filling stage.It should be noted that, unlike conditio

21、ns Eqs. 7 and 8, ensur-ing conditions Eqs. 9 and 10 are upheld in numerical implemen- tations becomes more difficult due to the following reasons:1. The surfaces at the same section have been meshed respec-tively, which

22、leads to a distinctive pattern of finite elements at the same section. Thus, an interpolation operation should be employed for u, v, T, P during the comparison between the two parts at the juncture.2. Because the two par

23、ts have respective flow fields with respectto the nodes at point A and point C (as shown in Fig. 2b) at the same section, it is possible to have either both filled or one filled (and one empty). These two cases should be

24、 handled separately, averaging the operation for the former, whereas assigning operation for the latter.3. It follows that a small difference between the melt-fronts ispermissible. That allowance can be implemented by ti

25、me al- lowance control or preferable location allowance control of the melt-front nodes.4. The boundaries of the flow field expand by each melt-frontadvancement, so it is necessary to check the condition Eq. 10 after eac

26、h change in the melt-front.5. In view of above-mentioned analysis, the physical parame-ters at the nodes of the same section should be compared and adjusted, so the information describing finite elements of the same sect

27、ion should be prepared before simulation, that is, the matching operation among the elements should be pre- formed.2.2.2 Numerical implementationPressure field. In modeling viscosity η, which is a function of shear rate,

28、 temperature and pressure of melt, the shear-thinning behavior can be well represented by a cross-type model such as:η(˙ γ, T, P) = η0(T, P)1+?η0 ˙ γ?τ??1?n (11)where n corresponds to the power-law index, and τ? charac-