ASTM B362-91(1997)e1
(Test Method)Standard Test Method for Mechanical Torque Rate of Spiral Coils of Thermostat Metal
Standard Test Method for Mechanical Torque Rate of Spiral Coils of Thermostat Metal
SCOPE
1.1 The test method covers the principles of determining the mechanical torque rate of spiral coils of thermostat metal. Note 1-This test method has been developed particularly to cover the determination of the mechanical torque rate of spiral coils made of thermostat metal for carburetors and manifold heat controls. The method is not limited to thermostat metals and can be used for spiral coils of other materials for which the torque rate must be measured accurately.
1.2 The values stated in inch-pound units are to be regarded as the standard. The metric equivalents of inch-pound units may be approximate.
1.3 This standard does not purport to address all of the safety concerns, if any associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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e1
Designation: B 362 – 91 (Reapproved 1997)
Standard Test Method for
Mechanical Torque Rate of Spiral Coils of Thermostat Metal
This standard is issued under the fixed designation B 362; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Keywords were added editorially in May 1997.
1. Scope outer end of the coil at a fixed radius.
1.1 The test method covers the principles of determining the
4. Significance and Use
mechanical torque rate of spiral coils of thermostat metal.
4.1 This test method is useful to determine the mechanical
NOTE 1—This test method has been developed particularly to cover the
force of spiral coils of thermostat metal.
determination of the mechanical torque rate of spiral coils made of
4.2 The mechanical properties of a coil may vary from lot to
thermostat metal for carburetors and manifold heat controls. The method
lot of thermostat metal material. This method is useful for
is not limited to thermostat metals and can be used for spiral coils of other
determining the optimum thickness and length of the material
materials for which the torque rate must be measured accurately.
for a given mechanical torque specification.
1.2 The values stated in inch-pound units are to be regarded
4.3 This test is useful as a quality test to determine accep-
as the standard. The metric equivalents of inch-pound units
tance or rejection of a lot of thermostat metal coils.
may be approximate.
1.3 This standard does not purport to address all of the
5. Apparatus
safety concerns, if any, associated with its use. It is the
5.1 The determination of the mechanical torque rate of
responsibility of the user of this standard to establish appro-
spiral coils is subject to many variables and is sensitive to the
priate safety and health practices and determine the applica-
degree that even different apparatus employing the same test
bility of regulatory limitations prior to use.
principles will give different results. Therefore it is recom-
mended that the apparatus be standardized. The apparatus
2. Terminology
shown in Fig. 1 and Fig. 2 and consisting essentially of the
2.1 thermostat metal—a composite material, usually in the
following components, has been found satisfactory:
form of sheet or strip, comprising two or more materials of any
5.1.1 Specimen Holder—A specimen holder shall provide
appropriate nature, metallic or otherwise, that, by virtue of the
for securely holding the inner end of the test specimen.
differing expansivities of the components, tends to alter its
Preferably, the holder or mounting arbor shall be of circular
curvature when its temperature is changed.
cross section whose diameter is as large as possible without
2.2 mechanical torque rate—the ratio of torque to deflec-
touching the inner turn of the coil under any test conditions of
tion. It is a measure of the stiffness of the coil and may have the
load. The end of the arbor shall be slotted entirely across its
units of ounce inch or gram centimetre per angular degree.
diameter, to a depth greater than the width of the specimen, and
2.3 spiral coil—a part made by winding strip on itself.
of a width slightly narrower than the thickness of the specimen.
Thus, the inner tab will be a push or snug fit in the slot for its
3. Summary of Test Method
entire width. The edges of the slot shall be sharp where it
3.1 The test for mechanical torque rate of spiral coils
intersects the circumference of the arbor. The slot shall be so
consists of applying a torque, or moment of force, that will not
positioned in the arbor that the center of rotation of the arbor
stress the material in excess of its elastic limits, to the coil and
and the coil will coincide.
measuring the resulting deflection as angular rotation. Of the
5.1.2 Protractor—The angular deflection due to the test
several methods for obtaining this value, it is preferred that the
torque shall be measured by a protractor with a minimum
outer end of the spiral coil be held stationary, but not fixed, and
division of 0.5 angular degrees.
the inner end of the coil be rotated after applying a load to the
5.1.3 Loading Pin—The loading pin is the member by
means of which the load is applied to the outer end of the coil.
This test method is under the jurisdiction of ASTM Committee B-2 on The pin shall be preferably of circular cross section approxi-
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
mately ⁄32 in. (2.4 mm) in diameter. The distance from the
B02.10 on Thermostat Metals.
center line of the mounting arbor to the center line of the
Current edition approved Oct. 7, 1991. Published December 1991. Originally
loading pin shall be specified.
published as B 362 – 60 T. Last previous edition B 362 – 81 (1986).
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