1、Designation: B 389 81 (Reapproved 2004)Standard Test Method forThermal Deflection Rate of Spiral and Helical Coils ofThermostat Metal1This standard is issued under the fixed designation B 389; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the thermaldeflection rate of spiral and helical c
3、oils of thermostat metal.1.2 The values stated in inch-pound units are to be regardedas the standard. The metric equivalents of inch-pound unitsmay be approximate.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the
4、user of this standard to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhealth practices, and determine the applicability of regulatorylimitations p
5、rior to use.2. Referenced Documents2.1 ASTM Standards:2E 77 Test Method for Inspection and Verification of Ther-mometers3. Terminology3.1 thermostat metala composite material, usually in theform of sheet or strip, comprising two or more materials of anyappropriate nature, metallic or otherwise, that
6、, by virtue ofdiffering expansivities of the components, tends to alter itscurvature when its temperature is changed.3.2 thermal deflection ratethe ratio of angular rotation totemperature change. It is a measure of the coils thermalactivity. It may have the units of angular degrees per degreeFahrenh
7、eit, or Celsius, and is expressed by the equation D=(A2A1)/(T2T1) where A2and A1are angular positions attemperature T2and T1respectively.3.3 spiral coila part made by winding strip on itself. Fig.1 and Fig. 2 show typical spiral coils, which can be wound withthe low-expansive side inside or outside,
8、 mounted on thespecimen holder.3.4 helical coila part made by winding strip in a formwherein the plane of the width of the strip is parallel to theaxial length. Fig. 3 shows a typical helical coil, which can bewound with the low-expansive side inside or outside, andright-hand or left-hand, mounted o
9、n the specimen holder.4. Summary of Test Method4.1 The test for thermal deflection rate of spiral and helicalcoils consists of measuring the angular rotation that a coilundergoes in response to a known temperature change.5. Significance and Use5.1 This test method simulates, to a practical degree, t
10、heoperation of the thermostat metal coil.5.2 The thermal deflection properties of a coil may varyfrom lot-to-lot of thermostat metal material. This method isuseful for determining the optimum thickness and length of thematerial for a given deflection specification.5.3 This method is useful as a qual
11、ity test to determineacceptance or rejection of a lot of thermostat metal coils.6. Apparatus6.1 Temperature BathA stirred liquid bath or uniformlyheated enclosure in which the specimen and mounting fixturecan be placed shall be used. An adjustable heating source isdesirable for maintaining the speci
12、men at the desired tempera-tures with a variation in temperature throughout the specimennot to exceed 0.5F (0.3C).6.2 ProtractorThe angular position at each test tempera-ture shall be measured by a protractor with a minimum divisionof 0.5.6.3 Temperature-Measuring ApparatusThe apparatus formaking te
13、mperature measurements shall be of such accuracythat the individual temperatures shall be known to be within60.5F (60.3C).6.4 Specimen HolderThe preferred methods of holdingspiral and helical coils are as follows:1This test method is under the jurisdiction of ASTM Committee B02 onNonferrous Metals a
14、nd Alloys and is the direct responsibility of SubcommitteeB02.10 on Thermostat Metals and Electrical Resistance Heating Materials.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1962. Last previous edition approved in 1981 as B 389 81 (1998).2For referenced ASTM stan
15、dards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、PA 19428-2959, United States.6.4.1 Spiral CoilsThe specimen holder for spiral coilsshall provide means for securely holding the coil. Althoughother means of support are possible, the holder or mountingarbor shall be preferably circular cross section whose diametershall be as large as possible withou
17、t touching the inner turn ofthe coil under any conditions of test temperatures. The arborshall be slotted across its diameter and to a depth greater thanthe width of the specimen. The width of the slot shall beslightly narrower than the thickness of the specimen so that theinner tab will be a push o
18、r snug fit in the slot. The edges of theslot shall be sharp where it intersects the circumference of thearbor. The slot shall be so positioned in the arbor that the centerof rotation of the coil and the center of the arbor coincide.6.4.2 Helical CoilsThe specimen holder for helical coilsshall provid
19、e means for securely holding the coil. Althoughother means of support are possible, the coil shall be held withits axis in a vertical position, the bottom end of the coil securedand the top end allowed to rotate freely with a temperaturechange. Preferably the end of the coil with the center tab shal
20、lbe considered the bottom and secured by clamping or press-fitting the tab into a slotted arbor similar to that described in6.4.1 for spiral coils. The depth of the slot shall be such that thefull height of the tab shall be held. If the coils do not have acenter tab, the arbor shall contain provisio
21、ns for attaching thecoil with screws, rivets, or by welding. A transmission pointercan be affixed to the top end. The center line of the coil, thetransmission pointer, and the protractor shall coincide.6.4.3 Deviations from these procedures of holding may benecessary when simulating the mounting use
22、d in the device forwhich the coil was designed, or in cases where coils are pressfitted on arbors. In these cases, the details of mounting shouldbe mutually agreed upon between the manufacturer and thepurchaser.6.5 Transmission Pointer:6.5.1 Spiral CoilsTo the outer end of the spiral coil shallbe at
23、tached a pointer that will transmit the rotation of the coilso that it can be read on the protractor. The pointer shall be oflightweight construction and attached to the coil by suitablemeans so that the movement of these portions of the coil thatdo not normally contribute to the movement of the coi
24、l with atemperature change shall not influence the rotation of thepointer. The pointer, when using the fixture shown in Fig. 1,shall be so positioned that its tip shall ride slightly above thedivisions of the protractor, but shall not touch the protractor atany time during the test. The pointer, whe
25、n using the fixtureshown in Fig. 2, shall be of sufficient length so that the top mayprotrude from the bath when the coil is submerged. The pointerfor either method, shall be so positioned that it will be in linewith the radius of the protractor and the specimen.6.5.2 Helical CoilsTo the free end of
26、 the helical coilsshall be attached a shaft that will transmit the rotation of thecoil so that it can be read on the protractor. The shaft canconsist of a wire or rod and shall be of lightweight construc-tion. It shall be attached to the coil by a suitable means so thatthe movement of those portions
27、 of the coil that does notnormally contribute to the movement of the coil with atemperature change shall not influence the rotation of the shaft.The transmission shaft shall be so located that its main axiscoincides with the center line of the coil. It shall be at rightangles to the plane of the pro
28、tractor and shall pass through itscenter. The end of the transmission shaft shall be so bent or anextension pointer so attached at right angles to the main bodyof the transmission shaft that its tip shall ride slightly above thedivisions on the protractor, but shall not touch the protractor atany ti
29、me during the test.6.5.3 The angular position of the pointer shall be known toan accuracy of 0.25 at each test temperature.7. Sampling7.1 Test for thermal deflection rate shall be taken in amanner to assure representative sampling of the test lot. A lot,for quality control purposes, comprises of the
30、 finished yield ofone bonded coil of material. Sampling shall consist of partsmade from each cut of material across the bonded width.Frequency of sampling shall be mutually agreed upon betweenthe manufacturer and the purchaser.8. Procedure8.1 After all forming operations and before testing, subjectt
31、he specimen to a stabilizing heat treatment to relieve internalstresses. This treatment shall consist of heating the specimen,while free to rotate, for a prescribed time and temperature. Thedetails of the stabilizing procedure will depend upon thecharacteristics of the thermostat metal being tested
32、and shall bemutually agreed upon between the manufacturer and thepurchaser.FIG. 1 Spiral CoilB 389 81 (2004)28.2 Mount the specimen with the pointer attached on thespecimen holder. Place the specimen holder with the specimenin the first bath of the desired temperature. When temperatureof the specime
33、n has reached the bath temperature, measure andrecord the angular position of the transmission pointer and thebath temperature.8.3 Establish the next chosen temperature and measure andrecord the position of the pointer and the bath temperature.9. Calculation9.1 Calculate the thermal deflection rate
34、as follows:D 5 A22 A1!/T22 T1!where:D = thermal deflection rate,A2= final angular position of pointer,A1= initial angular position of pointer,T2= final temperature corresponding to position A2, andT1= initial temperature corresponding to position A1.10. Report10.1 The report shall include the follow
35、ing:10.1.1 Type of thermostat metal,10.1.2 Dimensions of material,10.1.3 Dimensions of coil,FIG. 2 Spiral CoilB 389 81 (2004)310.1.4 Temperature and time of stabilizing heat treatment,10.1.5 Dimensions of arbor,10.1.6 Temperature range of test, and10.1.7 Thermal deflection rate.11. Precision and Bia
36、s11.1 The reliability of the results of the thermal deflectionrate depends on the method and apparatus. The most commonsources of variations in test results are (1) bath temperaturenonuniformity, (2) unverified temperature measuring appara-tus, and (3) parallax when reading the angle.11.2 The bias o
37、f test is that prescribed in Section 6 for thequality of apparatus.12. Keywords12.1 helical coil; spiral coil; thermal deflection rate; ther-mostat metalASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. U
38、sers of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed eve
39、ry five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible techn
40、ical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
41、en, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 3 Helical CoilB 389 81 (2004)4
