Figure 9a. External Bolting Prevents EMI Leakage
图 9a.用于防止 EMI 泄漏的外部螺栓
Figure 9b. Insert Pressed-In and Flared Makes EMI Tight Joint (Alternate: Weld or Cement with Conductive Epoxy)
图 9b.用于形成防 EMI 泄漏接缝的插入件(替代方式：焊接或使用导电环氧胶粘合）
2. Shaped or Molded Gaskets
2. 成型或模制垫片
Groove designs for O- or D-shaped configurations are effective because gasket deflection can be controlled and larger deflections can be accommodated. O-ring cross sections are preferred because they can be deflected more easily under a given load. D-shapes or rectangular cross sections are excellent for retrofit applications because they can be made to accommodate almost any groove cross section. Groove designs also provide metal-to-metal flange contact for superior shielding, and require fewer fasteners, thereby minimizing the number of paths where direct leakage can occur.
对于 O 型或 D 型垫片，开槽设计非常有效，因为其可有效地控制垫片变形，同时，可允许垫片有更大的变形量。宜首选 O 型圈截面，因为其在特定负载下，更易于发生变形。D 型或矩形截面非常适于改装应用，因为它们可适用于几乎所有的开槽截面。同时，开槽设计还可为金属法兰之间的接触提供极佳的屏蔽效果，同时需要更少的紧固件，因此，可最大程度地降低可能发生直接泄漏的通道数目。
Fasteners should be located such that pressure distribution is uniform at the corners (see Figure 10).
紧固件的位置应保证角部的压力分布均匀（见图 10）。
3. hollow Gaskets
3. 空心垫片
Hollow gasket configurations are very useful when large gaps are encountered, or where low closure forces are required. Hollow gaskets are often less expensive, and they can be obtained with or without attachment tabs. Hollow gaskets with tabs are referred to in the text and in the tables as “P-gaskets”. The minimum wall thickness of hollow gaskets is 0.020 in. depending on material. Contact XXXX ’ Applications Department for details. Hollow gaskets will compensate for a large lack of uniformity between mating surfaces because they can be compressed to the point of eliminating the hollow area.
当遇到较大的空隙或需要较低的闭合力时，空心垫片非常有用。空心垫片一般价格较低，可带或不带固定凸耳。带凸耳的空心垫片在文中和表格中被称为“P 型垫片”。根据材料的不同，空心垫圈的最小壁厚为 0.020 英寸。如需详细说明，请联系 XXXX 公司的应用部门。空心垫片因为可被压紧至消除空心区域，将可补偿配合表面之间较大的不均匀性。
Figure 10. Fastener Location Near Corners
图 10 靠近角部的紧固件位置
4. Compression limits
4. 压紧极限
When compression cannot be controlled, compression stops should be provided to prevent gasket rupture caused by over-compression. Grooves provide built-in compression stops. Figure 11 gives nominal recommended compression ranges for CHO-SEAL and CHO-SIL materials, assuming standard tolerances.
当无法控制压紧时，应提供压紧挡块，以防止因过压紧导致垫片破裂。开槽可以提供内嵌的压紧挡块。图 11 所示为 CHO-SEAL 和 CHO-SIL 材料（假定为标准公差）的建议标称压紧范围。
华译网上海翻译公司曾经翻译过大量有关成型或模制垫片资料文件，Beijing Chinese Subtitling Translation Service Agency has translated many technical documents about Shaped or Molded Gaskets.
Figure 11. Gasket Deflection Ranges (mm dimensions in parentheses)
图 11 垫片变形范围（括号内尺寸单位为 mm）
5. Elongation
5. 伸长率
The tensile strength of conductive elastomer gaskets is not high. It is good practice to limit elongation to less than 10 percent.
导电橡胶垫片的抗张强度不高。宜将伸长率限制到小于 10％ 的范围。
6. Splicing
6. 拼接
When grooves are provided for gasket containment, two approaches are possible. A custom gasket can be molded in one piece and placed into the desired groove, or a strip gasket can be spliced to length and fitted to the groove. To properly seat a spliced solid “O” cross section gasket, the inner radius of the groove at the corners must be equal to or greater than 1.5 times the gasket cross section width. Other cross sections need greater inner radius and may not be practical due to twisting when bent around corners. Splices can be simply butted (with no adhesive) or bonded with a conductive or non-conductive compound. If it has been decided that a spliced gasket will provide a satisfactory seal, the decision between splicing and molding should be based on cost, flash and tolerance. When a standard extrusion is available, splicing is generally recommended. For custom extrusions, splicing is generally more cost effective in quantities over 500 feet.
当提供有用于垫片安装的开槽，可通过两种方式实现。 定制垫片可模制成整体件并安装于要求的开槽中，或是可将垫片条拼合成所需长度，然后安装于开槽中。为了保证拼合的“O”型实心垫片能够正确落位，角部开槽的内径必须等于或大于垫片截面宽度的 1.5 倍。其他截面类型需要更大的内径，同时，由于弯角处弯曲时易于发生扭曲，可能不适用。拼接可为简单的对接（不使用粘合剂）或通过导电或不导电的化合料粘接。如果已经确定拼接的垫片可以提供满意的密封效果，则应根据费用、余料和公差确定是采用拼接还是模制垫片。当可使用标准挤压件时，一般建议采用拼接方式。对于定制挤压件，当数量超过 500 英尺时，通常拼接方式具有更好的成本效率。
7. Gasket limitations imposed by Manufacturing Methods
7. 加工方法对垫片的限制
Current manufacturing technology limits conductive elastomer gasket configurations to the following dimensions and shapes :
当前的加工技术将导电橡胶垫片限制为以下几种尺寸和形状：
Die-cut Parts
模切件
Maximum Overall Size: 32 in. long x 32 in. wide x 0.125 in. thick (81 cm x 81 cm x 3.18 mm)
最大外形尺寸：32 英寸长 x 32 英寸宽 x 0.125 英寸厚 (81 cm x 81 cm x 3.18 mm)
Minimum Cross Section: Width-tothickness ratio 1:1 (width is not to be less than the thickness of the gasket).
最大截面：宽厚比 1:1 （垫片宽度不得小于厚度）
Molded Parts
模制件
Currently available in any solid cross section, but not less than 0.040 in. in diameter. The outer dimensions of the gasket are limited to 34 inches in any direction. Larger parts can be made by splicing. Molded parts will include a small amount of flash (0.008 in. width and 0.005 in. thickness, maximum).
当前可提供各种规格的实心截面，但直径不可小于 0.040 英寸。垫片外径在各方向内限制为 34 英寸。部件尺寸越大，越可通过拼接方式实现。模制件会包含少量的飞边（最大宽 0.008英寸，厚 0.005英寸）。 |
