【考案の詳細な説明】[Detailed explanation of the idea]
(イ) 考案の技術分野
この考案は膨張黒鉛を主体とする密封部材に係
り、特に静的部分の密封に好適な密封部材に関す
る。
(ロ) 従来技術
従来グラフオイル（米国ユニオンカーバイト社
の商品名）等で知られている膨張黒鉛のみからな
るパツキンは知られており、このようなパツキン
を例えばグランドパツキンとしてバルブ、ポンプ
等の流体機器の軸封部即ち、軸とケーシングとで
形成される室内に複数個詰込むことにより流体が
機外に洩れるのを防止している。
そして膨張黒鉛のみからなるグランドパツキン
は、柔軟性と黒鉛がもつ自己潤滑性等の特性を活
用できるので比較的優れたものである。
しかし乍ら、膨張黒鉛のみから成型したパツキ
ンは締付け時、隙間よりパツキンがはみ出す現象
が見られた。
このような現象は、締付圧や使用される流体圧
力が高くなる程顕著に見られ、その結果体積減少
による応力緩和からシール特性が劣化し、液漏れ
につながる欠点があつた。
第１図はこのはみ出し現象を示すもので、１は
軸、２はボツクス、３はパツキン、４は押え金
具、５ははみ出したパツキンを示す。
ところで、係るはみ出し現象は、前述した膨張
黒鉛単味の成型パツキンに限らず、例えば、特開
昭55−126160号公報に開示されているような、パ
ツキン内部に補強材を備えている、成型パツキン
の場合でも顕著にみられる。
また、他の従来技術として、特開昭57−25564
号公報に開示されている密封部材では、金属線を
交絡して編みあげた、断面輪状の金網内に、不定
形の目詰め材を充填した密封部材なので、成形面
圧を高めて、形付しても、目詰め材の流出によつ
て、密封部材としての形状保持性にやや劣り、応
力緩和をまねきやすく、膨張黒鉛単体による優れ
た封止機能を発揮させることが困難であつた。
さらに他の従来技術として、特開昭56−124766
号公報に開示されてる、自動車の排気管継手部に
好適な高温シールが開示されているが、係る密封
部材では、高温と耐振動性によいかも知れない
が、金網と膨張黒鉛とが、層状に巻かれて成形さ
れているため、金網を伝わつて流体の洩れ終絡が
形成されている状態となり、決してシール機能面
からは、シビアな密封部材でもなく、また、膨張
黒鉛のみの封止機能をも発揮されない憾みもあ
る。
(ハ) 考案の目的
この考案は膨張黒鉛成型体の優れたシール特性
をそのまま生かしながら、しかも応力緩和を招来
させる最大の起因であるはみ出し現象をなくしシ
ール性の良い優れた密封部材を提供することを目
的とする。
(ニ) 考案の構成
この考案は、流体機器の軸封部のボツクス内に
収容され、押え金具にて締込まれることによつて
流体を密封する密封部材において、断面が略矩形
の環状膨張黒鉛成型体の前記押え金具による締込
み方向の両端面に金属細線製編物からなるシート
を添着し、一体成型した膨張黒鉛製密封部材であ
ることを特徴とする。
(ホ) 実施例
以下この考案の一実施例を図面に基づいて詳述
する。
第２図は本考案の一例を示す斜視図で、６は膨
張黒鉛成型体、７は金属細線製編物からなるシー
トを示す。
金属細線製編物からなるシート７は、第１図の
上下の面、即ち膨張黒鉛のはみ出し５の生じる両
側面である押え金具４の締込み方向の両端面にの
み当接し、その他の膨張黒鉛のはみ出しの生じな
い面は金属細線編物からなるシート７が付与され
ず、膨張黒鉛成型体６が露出している。
この考案の密封部材は、先ず金属細線製編物か
らなるシート７をプレスして仮成型し、次いで膨
張黒鉛成型体６を上下の金属細線製編物からなる
シート７間にはさみプレスして成型し製造する。
次にこの考案の密封部材と膨張黒鉛単体のパツ
キンとのはみ出し特性の比較を次の実験例で示
す。
〔実験例 １〕
膨張黒鉛成型体の両端面に第２図に示す如く金
属細線（ステンレスSUS304、線径0.15mm、軟質）
製の編物からなるシートを、膨張黒鉛82重量％と
金属18重量％になる如く当接し一体成型した本考
案品のはみ出し重量は０重量％であつた。
これに対し膨張黒鉛単体のみからなるパツキン
を同様の条件にて実験をした結果、はみ出し重量
は0.5重量％であつた。
尚、上記実験結果の試験条件として初期締付面
圧は400Kg／cm2、流体圧力最大350Kg／cm2（ガスケ
ツト部の締付圧力は約1435Kg／cm2）圧力サイクル
５回、隙間0.1〜0.12mmであつた。
〔実験例 ２〕
水圧実験として、「水圧力：350Kg／cm2を１時間
保持し、その後水圧力：０Kg／cm2」を１サイクル
として、４サイクル繰返し実験をした。
試料として、本考案品は、実験例１と同じ構成
品
（サイズ、内径×外径×高さ
＝φ100mm×φ114mm×18.5mm）
を用い、比較品として、同サイズの膨張黒鉛シー
ト、ステンレス製の網状体を重ね合せて、うず巻
状に巻回して、成型したパツキン（表面部：膨張
黒鉛シート）を選んだ。
実験の結果は表−１に示す。
(a) Technical field of the invention This invention relates to a sealing member mainly made of expanded graphite, and particularly to a sealing member suitable for sealing static parts. (b) Prior art Packings made only of expanded graphite, known as Graph Oil (trade name of Union Carbide Company, USA), are known, and such packings are used as gland packings for valves, pumps, etc. By packing a plurality of seals into the shaft seal of a fluid device, that is, the chamber formed by the shaft and the casing, fluid is prevented from leaking outside the machine. A gland packing made only of expanded graphite is relatively excellent because it can take advantage of the flexibility and self-lubricating properties of graphite. However, when the gasket molded only from expanded graphite was tightened, there was a phenomenon in which the gasket protruded from the gap. Such a phenomenon becomes more noticeable as the tightening pressure and the fluid pressure used become higher, and as a result, the sealing properties deteriorate due to stress relaxation due to the volume reduction, resulting in a drawback that this leads to liquid leakage. FIG. 1 shows this protruding phenomenon, with reference numeral 1 indicating the shaft, 2 the box, 3 the packing, 4 the presser fitting, and 5 the protruding packing. By the way, such extrusion phenomenon is not limited to the above-mentioned molded packing made of expanded graphite alone, but also to molded packing provided with a reinforcing material inside the packing, for example, as disclosed in JP-A-55-126160. It is also noticeable in cases of In addition, as other conventional technology, Japanese Patent Application Laid-Open No. 57-25564
The sealing member disclosed in the publication is a wire mesh with a ring-shaped cross section made by interlacing metal wires, and filled with a filling material of irregular shape. However, due to the outflow of the plugging material, the shape retention as a sealing member was slightly inferior, stress relaxation was likely to occur, and it was difficult to exhibit the excellent sealing function of expanded graphite alone. Furthermore, as another prior art, JP-A-56-124766
A high-temperature seal suitable for an automobile exhaust pipe joint is disclosed in the above publication, but such a sealing member may have good high-temperature and vibration resistance, but the wire mesh and expanded graphite are layered. Because it is wound around and molded, the fluid leaks through the wire mesh and forms a termination point, so it is by no means a severe sealing member in terms of sealing function, and the sealing function of expanded graphite only. There is also a sense of regret that he is not able to demonstrate his true potential. (c) Purpose of the invention The purpose of this invention is to provide an excellent sealing member with good sealing properties while making full use of the excellent sealing properties of the expanded graphite molded body, and eliminating the extrusion phenomenon that is the biggest cause of stress relaxation. With the goal. (d) Structure of the invention This invention is a sealing member that is housed in a box of a shaft sealing part of a fluid device and is tightened with a presser fitting to seal the fluid. The molded body is characterized in that it is an expanded graphite sealing member integrally molded with sheets made of a knitted metal wire attached to both end faces of the molded body in the tightening direction by the presser fitting. (e) Embodiment An embodiment of this invention will be described below in detail based on the drawings. FIG. 2 is a perspective view showing an example of the present invention, in which 6 shows a molded expanded graphite body, and 7 shows a sheet made of a knitted fabric made of fine metal wires. The sheet 7 made of a knitted fabric made of fine metal wires contacts only the upper and lower surfaces in FIG. The sheet 7 made of the metal fine wire knitted fabric is not applied to the surface where no protrusion occurs, and the expanded graphite molded body 6 is exposed. The sealing member of this invention is manufactured by first pressing and temporarily forming a sheet 7 made of a knitted fabric made of fine metal wire, and then sandwiching and pressing an expanded graphite molded body 6 between upper and lower sheets 7 made of knitted fabric made of fine metal wire. do. Next, a comparison of the extrusion characteristics between the sealing member of this invention and a packing made of expanded graphite alone will be shown in the following experimental example. [Experiment Example 1] Thin metal wires (stainless steel SUS304, wire diameter 0.15 mm, soft) are placed on both end surfaces of the expanded graphite molded body as shown in Figure 2.
The protruding weight of the product of the present invention, which was formed by integrally molding a sheet made of a knitted fabric made of 100% by weight of expanded graphite and 18% by weight of expanded graphite and 18% by weight, respectively, was 0% by weight. On the other hand, as a result of experiments under similar conditions with a packing made only of expanded graphite, the protrusion weight was 0.5% by weight. The test conditions for the above experimental results are: initial tightening surface pressure of 400 Kg/cm 2 , maximum fluid pressure of 350 Kg/cm 2 (tightening pressure of gasket part is approximately 1435 Kg/cm 2 ), 5 pressure cycles, gap 0.1 to 0.12 It was warm in mm. [Experimental Example 2] As a water pressure experiment, 4 cycles were repeated in which ``water pressure: 350 Kg/cm 2 was maintained for 1 hour, and then water pressure: 0 Kg/cm 2 '' was set as one cycle. As a sample, the invented product used the same components as Experimental Example 1 (size, inner diameter x outer diameter x height = φ100 mm x φ114 mm x 18.5 mm), and as comparative products, expanded graphite sheet of the same size, stainless steel We selected a packing material (surface part: expanded graphite sheet) that was formed by overlapping the mesh bodies and winding them into a spiral shape. The results of the experiment are shown in Table-1.
【表】【table】
【表】
はみ出し重量
(注) はみ出し率(％)の計算＝
【table】
overhang weight
(Note) Calculation of protrusion rate (%) =