结构设计必读.pdf

Design Check Chart Start with DuPont DELRIN HYTREL MINLON RYNITEDELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEZYTEL DELRIN HYTREL MINLON RYNITE ZYTE HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL DELRIN HYTREL MINLON RYNITE ZYTEL HYTREL MINLON RYNITE ZYTEL DuPont Engineering Polymers d Checklist General Perance Requirements Structural, Aesthetic, etc. Combining Multiple Parts or Functions Structural Load Static, Dynamic, Cycling, Impact, etc. Environment Temperature, Time, Chemical, etc. Tolerance Requirements Life of Product Quantity of Product vs. Fabrication Process Secondary Operation Packaging and Shipping Environment Temperature Time Load Other Environments Chemical, Water, Humidity, etc. Engineering Design Facts Type of Load Frequency of Load Stress Rate Compression, Tensile, Flexural Strain Amplitude Load Deation Tensile, Compression, Shear, etc. Apparent Modulus Includes Strain Due to Creep Direction of Load Correlating Test Data With End Use Safety Factor Tests ATIM, SAE, UL, Etc. Tension Compression Creep Dynamic/Fatigue/Torsion Impact Poisson’s Ratio Electrical Continuous Service Temp./U.L. Temp. Index Material and Process Directional Flow Directional Layout of Reinforcements Regrinding Pre-drying Prototyping Machining, Molding Appearance Style Shape Color Surface Finish/Weld Lines/Flow Lines/ Parting Line/Gate Location Decoration Economic Factors Cost of Present Part Cost Estimate of Part in DuPont Engineering Plastics Faster Assembly and Elimination of Finishing Operation Redesign Part to Simplify Product WRONGRIGHTWRONGRIGHT Designing for Uni Walls Central gate Problem may be solved by proper web dimension. In some cases properly dimensioned ribs may be used to fill the exterior crown. 0.5T Gate WRONGRIGHTWRONGRIGHT Designing for Ribbed Walls Ribs Adequate ribbing can counteract bending. However, ribs should not be used unless necessary e.g., not for small modulus high precision gears. Stressed parts in a transparent material show, under polarized light, the stress concentration effect of sharp corners. Here are two alternative solutions; their choice will depend on the torque to be transmitted. Redesign has reduced high stress concentration in snap-fit area. Circular inserts with fine rounded knurling are preferred. They should not have sharp edges. Installing inserts after molding may also be a solution. WRONGRIGHTWRONGRIGHT Designing without Stress Concentration Metal insert 5N Wall WRONGRIGHTWRONGRIGHT Gate Location WRONGRIGHTWRONGRIGHT Designing for Assembly WRONGRIGHTWRONGRIGHT Designing with Clearance on Threads The two ways to solve this problem are A Locate the gate in the thicker section a long cycle may however be necessary to pack the cavity properly. B Core out the part. “L” should be kept larger at least – D, and a flat head screw would eliminate tan- gential stresses. A change in gate location could also help. Redesigned exterior snap-fit cap and addition of “O” ring eliminate leakage. No undercut in the mold. If the ratio LL1 increases, some ribs can be added. Engineering plastics usually resist compression stresses better than tensile stresses.Threads should be provided around the exterior diameter of the plastic part. An “O” ring ensures tightness. The “O” ring is compressed radially. Additional ways to control creep could be 1 Flanges may be stiffened by ribs, or 2 Metal rings all around, placed under the bolts. Self-tapping screw Relief allows snap-fit without breaking 1⁄32″ 1⁄32″ L 1 L PRESSURE Gate Printed in U.S.A. [Replaces H-30618-1] Reorder No. H-8107999.3DuPont Engineering Polymers d For more ination on Engineering Polymers For Automotive Inquiries800 533-1313 800 441-0575 Start with DuPont U.S.A. East DuPont Engineering Polymers Chestnut Run Plaza 713 P.O. Box 80713 Wilmington, DE 19880-0713 302 999-4592 Automotive DuPont Engineering Polymers Automotive Products 950 Stephenson Highway Troy, MI 48007-7013 313 583-8000 Asia Pacific DuPont Asia Pacific Ltd. P.O. Box TST 98851 Tsim Sha Tsui Kowloon, Hong Kong 852-3-734-5345 Canada DuPont Canada, Inc. DuPont Engineering Polymers P.O. Box 2200 Streetsville, Mississauga Ontario, Canada L5M 2H3 905 821-5953 Europe DuPont de Nemours Int’l S.A. 2, chemin du Pavillon P.O. Box 50 CH-1218 Le Grand-Saconnex Geneva, Switzerland Tel. 41 22 7175111 Telefax 41 22 7175200 Japan DuPont Kabushiki Kaisha Arco Tower 8-1, Shimomeguro 1-chome Meguro-ku, Tokyo 153 Japan 011 81-3-5434-6100 Mexico DuPont S.A. de C.V. Homero 206 Col. Chapultepec Morales 11570 Mexico D.F. 011-525-722-1456 South America DuPont America do Sul Al. Itapecuru, 506 AlphavilleCEP 06454-080 BarueriSo Paulo, Brasil Tel. 055-11 7266.8531/8647 Fax 055-11 7266.8513 Telex 055-11 71414 PONT BR DuPont Argentina S.A. Avda.Mitre y Calle 5 1884 Berazategui-Bs.As. Tel. 541 319-4484/85/86 Fax 541 319-4417 The data listed here fall within the normal range of properties, but they should not be used to establish specification limits nor used alone as the basis of design. The DuPont Company assumes no obligations or liability for any advice furnished or for any results obtained with respect to this ination. All such advice is given and accepted at the buyer’s risk. The disclosure of ination herein is not a license to operate under, or a recommendation to infringe, any patent of DuPont or others. DuPont warrants that the use or sale of any material that is described herein and is offered for sale by DuPont does not infringe any patent covering the material itself, but does not warrant against infringement by reason of the use thereof in combination with other materials or in the operation of any process. CAUTION Do not use in medical applications involving permanent implantation in the human body. For other medical applications, see “DuPont Medical Caution Statement,” H-50102.