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发表于 2016-3-22 20:49:25
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AGMA B89-2004
5.3.3 ControlWith Test Bars. Test bars are used
to show that the case properties and, when required,
core propertiesmeet specifications. Test bars should
be of the same steel type as the gear(s), but not necessarily
the same heat. Bars should accompany gearing
through all heat treatments, including all post hardening
treatments. Consideration should be given to
evaluation of that portion of the case that is not removed
during tooth finishing.
A section, with a ground and polished surface
(normal, at mid length of a test bar), is considered
satisfactory for determining effective case depth of
carburized helical and spur gearing to 4 1/2DP.The
test bar should haveminimumdimensions of 5/8 inch
(16 mm) diameter by 2 inch (50 mm) long. One inch
(25 mm) diameter¢2.0 inch (50 mm) long bar may
be used for coarser pitch carburized gearing to 1.5
DP. The size of the bar for coarser than 1.5 DP gearing
should be mutually agreed upon, and should
approximate the inscribed diameter atmid height of
the tooth cross section. The bar length should be
2---3 times the diameter.
When specified, core hardness and core microstructure
can be determined at the center of the
round bar size shown in Table 5---1 according to diametral
pitch.
Test discs or platesmay also be used whoseminimum
thickness is 70 percent of the appropriate test
bar diameter. Theminimuminscribed diameter on a
test disc (or plate dimensions) should be a minimum
of three times its thickness.
The recommended test bar diameter for bevel
gearing is to be approximately equal to the inscribed
diameter of the normal tooth thickness at mid face
width.
When disagreement exists as to the properties
obtained on the test bar and the parts, an actual part
may be sectioned for analysis.
测试试样常用于检测工件的实际性能是否符合产品规范，测试试样必须和齿
轮工件的材料保持一致，但热处理没有必要一模一样。试样应该和齿轮工件一同
进行热处理，包括后续的热处理工艺。需要注意的是在后续的齿面修型过程中要
保证渗层没有被磨掉。
一般对于渗碳直齿和斜齿轮，如果用于检测有效硬化层深度的测试试样经抛
光后截面尺寸（一般在试样的中间部位剖开）能达到5.62倍模数（直径尺寸，单
位是mm，GBT8539 上推荐的是6倍模数）就算合格。测试试样的最小规格应该是
φ16mm×50mm，对于径节达到1.5（6-17）的大模数的齿轮可以使用φ25mm×
50mm大规格尺寸试样。对于模数大于1.5径节（m＞17）的齿轮，测试试样的尺
寸应该由制造商和买方共同商定，其直径应该接近齿轮半齿高截面处对应的轮齿
内切圆直径（即直径=1/2齿高处的齿厚），长度应该为2-3倍的直径。
如果要求检测齿轮的心部硬度和心部显微组织，可以根据具体的径节尺寸在
试样的中心测定，详细可参见表5-1。
有时也会采用圆盘状或者饼状测试试样，试样的最小厚度应该是试样直径的
70%，而圆盘状（或者饼状）试样的最小内切圆直径应该为厚度的三倍。
对于伞齿轮的测试试样，其直径应该等于正常齿厚、半齿宽处对应的内切圆
直径。
如果试样的测试结果无法满足要求，就必须对实际工件进行解剖分析。
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