DLA MIL-HDBK-660 B-2012 FABRICATION OF RIGID WAVEGUIDE ASSEMBLIES (SWEEP BENDS AND TWISTS).pdf

1、AMSC N/A FSC 5985 MIL-HDBK-660B 21 August 2012 SUPERSEDING MIL-HDBK-660A 7 July 1972 MILITARY STANDARDIZATION HANDBOOK FABRICATION OF RIGID WAVEGUIDE ASSEMBLIES (SWEEP BENDS AND TWISTS) This handbook is for guidance only. Do not cite this document as a requirement. INCH-POUND Provided by IHSNot for

2、ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B FOREWORD 1. This handbook is approved for use by all Departments and Agencies of the Department of Defense. 2. This document provides information on methods of fabricating waveguide assemblies for rigid RF trans

3、mission lines. It provides information and guidance to personnel concerned with the fabrication of waveguide assemblies to fix equipments and circuits in the field. The handbook is not intended to be referenced to purchase specifications except for informational purposes, nor should it supersede any

4、 specification requirements. 3. Comments, suggestions, or questions on this document should be addressed to DLA Land and Maritime, ATTN: VAT, Post Office Box 3990, Columbus, OH 43218-3990, or emailed to Tubesampsdla.mil. Since contact information can change, you may want to verify the currency of th

5、is address information using the ASSIST Online database at https:/assist.dla.mil. ii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B CONTENTS SECTION Page 1. SCOPE 1 1.1 Scope 1 1.2 Purpose of handbook . 1 1.2.1 Purpose of handbook 1 1.

6、2.2 Design 1 1.2.3 Part or identifying number (PIN) 1 1.2.4 Marking 3 2. APPLICABLE DOCUMENTS . 5 2.1 General 5 2.2 Government documents . 5 2.2.1 Specification, standards, and handbooks 5 2.2.2 Other Government documents, drawings, and publications . 5 2.3 Non-Government publications . 5 2.4 Order

7、of precedence 5 3. DEFINITIONS (not applicable) . 7 4. GENERAL REQUIREMENTS (PREPARATION FOR BENDING AND TWISTING) . 7 4.1 Fabrication of template 7 4.1.1 Template materials 7 4.1.2 Conforming template shape . 7 4.2 Annealing . 7 4.2.1 Annealing brass waveguide . 8 4.2.2 Filling with gas before anne

8、aling( optional) 8 4.2.3 Annealing aluminum waveguide 8 4.3 Filling . 8 4.3.1 Alloy method 8 4.3.2 Rosin method . 9 4.4 Bending fabrication 9 4.4.1 Pines bending machine 10 4.4.1.1 Draw bending . 11 4.4.1.2 Metal mandrel . 11 4.4.1.2.1 Plug mandrel 11 4.4.1.2.2 Formed mandrel . 12 4.4.1.2.3 Ball man

9、drel 12 4.4.1.2.4 Cable mandrel 12 4.4.1.2.5 Universal mandrel . 13 4.4.1.2.6 Small line mandrel 13 4.4.1.3 Mandrel selection . 13 4.4.1.4 Improper tooling and setting . 13 4.4.1.5 Lubrication 15 iii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI

10、L-HDBK-660B CONTENTS Continued. SECTION . Page 4.4.1.6 Twisting and bending . 15 4.4.1.7 Mandrel material and finish 15 4.4.1.8 Polytetrafluoroethylene mandrel . 15 4.4.2 Wallance bending machine 16 4.4.3 Hydraulic push press and portable hydraulic bender method 19 4.4.4 Hand bending machine . 21 4.

11、4.5 Bench vise 22 4.5 Twisting of the waveguide 22 5. DETAILED REQUIRMENTS (PRE-ASSEMBLY, ASSEMBLY, FINISHING OPERATIONS) 25 5.1 Removal of filling 25 5.1.1 Alloy method 25 5.1.2 Rosin method . 25 5.2 Removal of dents and wrinkles from waveguide 26 5.3 Cutting . 26 5.3.1 Hacksaw 26 5.3.2 Power saw .

12、 26 5.3.3 Squareness of cut 26 5.3.4 Modification of flanges and heavy wall waveguides for proper fit 26 5.3.4.1 Cover flange . 26 5.3.4.2 Choke flange 27 5.4 Cleaning . 28 5.5 Attachment of flanges 28 5.5.1 Assembly of contact or cover flange to waveguide 28 5.5.2 Assembly of choke or socket flange

13、s to waveguide . 29 5.5.3 Clamps and jigs . 30 5.6 Silver brazing brass waveguide . 30 5.7 Brazing flanges on aluminum waveguide . 35 5.7.1 Torch tips . 36 5.7.2 Brazing rod 36 5.8 Dip brazing aluminum waveguide 36 5.8.1 Brazing flux 36 5.8.1.2 Preparation of parts 36 5.8.1.2.1 Cleaning . 36 5.8.1.2

14、.2 Chemical dipping 36 5.8.2 Assembly . 37 5.8.2.1 Final cleaning . 37 5.9 Dry air piping connections 37 5.9.1 Air connection completion 37 5.10 Finishing operation. 37 5.10.1 Finishing operation. 37 5.10.1.1 Machining . 37 5.10.1.2 Smoothing 37 5.10.2 Cleaning waveguide 37 iv Provided by IHSNot for

15、 ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B CONTENTS continued SECTION . Page 6. NOTES . 39 6.1 Intended use 39 6.2 Subject term (key word) listing . 39 6.3 Changes from pervious issue 39 v Provided by IHSNot for ResaleNo reproduction or networking permi

16、tted without license from IHS-,-,-MIL-HDBK-660B ILLUSTRATIONS Figure . Page 1. Waveguide side and bend identification 2 2. Electrical length of bend 4 3. Wooden waveguide template 6 4. Wire template 6 5. Template for waveguide twist 7 6. Wall distortion of bend. 10 7. Draw bend . 11 8. Types of mand

17、rels 12 9. Undersize plug mandrel setting . 12 10. Wrinkling caused by tapered mandrel . 14 11. Mandrel setting too deep. 14 12. Inherent gap between tangent point and lip of wiper die . 14 13. Depth of support of plug, form, and ball mandrels 15 14. Details of bending forms for Wallace bending mach

18、ine 17 15. Bending forms for edgewise bend for 3 x 1.5 inch guide. 17 16. Detail of bending forms for edgewise bends for 3 x 1.5 inch guide . 18 17. Bending form for sideways bend for 3 x 1.5 inch guide . 18 18. Detail of forms for sideways bend . 18 19. Greenlee hydraulic bender, model 775 . 20 20.

19、 Bending waveguide in simple hydraulic press . 20 21. Waveguide dies used with Greenlee bender . 21 22. Waveguide hand bending tool . 22 23. Twisting machine for waveguide . 22 24. Twisting machine detail . 23 25. Cross section of clamps for 3 x 1.5 inch waveguide twisting machine 24 26. Waveguide t

20、wisting tool for 3 x 1.5 inch waveguide 24 27. Tool for use with twisting machine 25 28. Modifying standard RG-95/U heavywall aluminum waveguide for use with standard US-406A/U choke flange 27 29. Modification of standard UG-406A/U choke flange for use with standard RG-95/U heavywall Aluminum wavegu

21、ide . 28 30. Through flange on waveguide . 29 31. Concentricity of waveguide and flange . 30 32. Squareness of flange face with waveguide . 31 33. Waveguide and flange assembly-butt design 32 34. Waveguide squareness. 33 35. Torch brazing 34 36. Jig for through flange 34 37. Silver soldering wavegui

22、de and flange-sleeve design . 35 38. Directing flame on contact or cover flange 35 39. Brazing waveguide and flange-butt design . 37 40. Fitting for air connection 38 vi Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B TABLES Table I Wav

23、eguide bend values 2 II. Surface toughness tolerances of waveguides . 38 vii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B 1 1. SCOPE 1.1 Scope. This handbook is intended for the electronic installations technician to be used as a gui

24、de for fabricating rectangular waveguide bends and twists used in the microwave region of the electronic spectrum. a. Where bends and twists are required in equipment, it may not always be possible to obtain bends and twists of the exact lengths or radii required because they are not standard, and t

25、herefore are not carried in supply, or manufactured by industry as a stock item. By using the techniques described in this handbook, such bends and twists can be fabricated in the field, and the equipment for which they are intended can be placed in service in a shorter time than purchased parts cou

26、ld be supplied. b. This handbook describes the assembly and finishing of components fabricated from the two most commonly used materials, brass and aluminum. The processes and methods used in the fabrication of waveguide assemblies from other materials are similar to the procedures described herein.

27、 Careful attention should be paid, however, to brazing only the components made from similar metals to prevent the possibility of galvanic action between parts. 1.2 PURPOSE OF HANDBOOK 1.2.1 Purpose of handbook. For purposes of this handbook, the term twists means a waveguide configuration similar t

28、o those shown in figures 23 and 24. These illustrations should enable a technician to differentiate between twists and those waveguide assemblies that are constructed by ready-made elbows and sweep bends. 1.2.2 Design. Waveguides are supplied in straight lengths of from 6 to 14 feet, but usually the

29、 length is 10 feet. The number of joints or couplings in a run should be kept to a minimum in order to obtain the most efficient electrical transmission. In an installation, there will be a need for bends, twists, and off-sets. Since all conditions cannot be met with standard fittings, it is desirab

30、le to be able to form bends and twists in the straight sections of the waveguide. These can be formed in the full straight lengths by the methods described in this handbook. a. Bending of corrosion-resisting steel or magnesium waveguides is not permissible. b. Ordinarily, bends and twists should not

31、 be sharper than those given in table I, but it is possible to make sharper bends and twists than specified herein without causing excessive attenuation, provided that reflections are avoided. This is done by forming the bend so that its electrical length (mean “L” in figure 2) is exact multiple of

32、waveguides half wavelengths, and preferably at the midband of the frequency at which it is to operate. This will cause the reflection at either end of the bend to cancel out. Similarly, twists may be so designed that their length is an exact multiple of waveguide half wavelengths. 1.2.3 Part or Iden

33、tifying number (PIN). Proper identification of waveguide bends referenced herein is provided in figure 1. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B 2 FIGURE 1. Waveguide side and bend identification. TABLE I. Waveguide bend values

34、. Waveguides Bending radius Dimension 23 to 6.5 inches Use manufactured elbows N/A 6.5 x 3.25 inches Minimum bending radius “E” or “H” Minimum length for 90-degree twist Maximum inside wall variance 24 inches 36 inches .125 inch 3 x 1.5 inches Minimum bending radius “E” or “H” Minimum length for 90-

35、degree twist Maximum inside wall variance 18 inches 3 inches .062 inch 1 x 3 inches RG 109/U Minimum bending radius “E” No “H” bends, use manufactured elbows Minimum length for 90-degree twists Maximum inside wall variance 12 inches 30 inches .062 inch Provided by IHSNot for ResaleNo reproduction or

36、 networking permitted without license from IHS-,-,-MIL-HDBK-660B 3 TABLE I. Waveguide bend values - Continued. Waveguides Bending radius Dimension .750 x 1.5 inches M85/1-067-XXX (RG 50/U) M85/1-065-XXX (RG-106/U) Minimum bending radius, “E” No “H” bends, use manufactured elbows Minimum length for 9

37、0-degree twist Maximum inside wall variance 12 inches 15 inches .031 inch .625 x 1.125 inches Minimum bending radius, “E” Minimum bending radius, “H” Minimum length for 90-degree twist Maximum inside wall variance 6 inches 12 inches 18 inches .031 inch 1.5 x .5 inches RG 110/U Minimum bending radius

38、 “E” or “H” Minimum length for 90-degree twist Maximum inside wall variance 6 inches 15 inches .031 inch 1.2.4 Marking. Unless conditions make it absolutely necessary, never make a bend or twist sharper than the specified minimum. Under no conditions should the radius of a bend or twist be less than

39、 one full wavelength of the center frequency for any waveguide. The reflections caused by poorly matched bends can result in a high standing wave ratio. = 30,000 = 11,808 EXAMPLE A: The radii of preformed bends for M85/1-043-XXX (RG 48/U) is 7.5 inches (191 mm), whereas, the radii of bends formed fo

40、r M85/1-043-XXX (RG 48/U) TE10mode wavelength range (lowest to highest recommended operating frequency) is from 4.539 to 2.987 inches (115.29 to 75.87 mm). The mean wavelength is 3.763 inches (96 mm) and a waveguide half wavelength is 1.8815 inches (47.790 mm). Any multiple of 1.8815 inches (47.790

41、mm) that generates a radius greater than 7.5 inches (191 mm) should be used as the mean electrical length of a formed bend for M85/1-043-XXX (RG 48/U) waveguide. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B 4 FIGURE 2. Electrical len

42、gth of bend. To determine the radius of a 90-degree bend, the following calculations are made. From the above formula in Example A: = 909032.57LRLRL= 0.637L Referring to M85/1-043-XXX (RG 48/U), operating in the TE10mode where RLis greater than 7.5 + 2ainches, where R = 7.5 inches and L is a multipl

43、e of 2. = 3.763 inches, 2= 1.8815 inches, a = 1.34 inches, b = 2.84 inches, c = 1.5 inches for an “E“ bend. Then let L = 6 x 2= 11.289 inches, then RL= 0.637 x 11.289 = 7.2 inches and R = 6.44 inches. Since the resultant value is less than 7.5 inches, the radius cannot be used. Based on similar comp

44、utations, when: L = 7 x 2= 13.170, RL= 8.39, R = 7.64 inches L = 8 x 2= 15.05, RL= 9.588, R = 8.838 inches and so forth; hence, the radii computed for a value of L which is a multiple of 2of 7 or greater may be used. For an “H“ bend, c = 3.0 inches when: L = 7 x 2= 13.170, RL= 8.39, R = 6.89 inches

45、L = 8 x 2= 15.05, RL= 9.588, R = 8.09 inches and so forth; hence a value of L which is a multiple of 2of 8 or greater may be used. L = mean electrical length c = height or width of outer dimension of waveguide depending on plane of bend. b = larger dimension of waveguide Provided by IHSNot for Resal

46、eNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-660B 5 2. APPLICABLE DOCUMENTS 2.1 General. The documents below are not necessarily all of the documents referenced herein, but are those needed to understand the information provided by this handbook. 2.2 Government docu

47、ments. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. FEDERAL SPECIFICATIONS O-F-499 - Flux, Brazing (Silver Brazing Filler Metal, Low Melting Point). QQ-B-654 - Brazing, Alloys, Silver. DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-DTL-3970 - Waveguide Assemblies, Rigid, General Specification for. (Copies of these documents are available