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時間:2020-07-10 コメント: 41

A screw, or bolt, is a type of fastener, typically made of metal, and characterized by a helical ridge, known as a male thread (external thread) or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as a female thread (internal thread), often in the form of a nut or an object that has the internal thread formed into it. Other screw threads are designed to cut a helical groove in a softer material as the screw is inserted. The most common uses of  Screws  are to hold objects together and to position objects.

ねじのほとんどの場合、一端にヘッドがあり、工具で回転または駆動できるように特別に形成された形状が含まれています。 ねじを打ち込むための一般的な工具には、ドライバーとレンチが含まれます。 ヘッドは通常、ねじの本体よりも大きいため、ねじがねじの長さよりも深く打ち込まれないようにし、座面を提供します。 例外があります。 例えば、 キャリッジボルト have a domed head that is not designed to be driven; set screws often have a head smaller than the outer diameter of the screw; J- Bolts  have a J-shaped head which is not designed to be driven, but rather is usually sunk into concrete allowing it to be used as an anchor bolt. The cylindrical portion of the screw from the underside of the head to the tip is known as the shank; it may be fully threaded or partially threaded.[1] The distance between each thread is called the "pitch".

The majority of screws are tightened by clockwise rotation, which is termed a right-hand thread; a common mnemonic device for remembering this when working with screws or bolts is "righty-tighty, lefty-loosey." Screws with left-hand threads are used in exceptional cases. For example, when the screw will be subject to counterclockwise torque (which would work to undo a right-hand thread), a left-hand-threaded screw would be an appropriate choice. The left side pedal of a bicycle has a left-hand thread.

More generally, screw may mean any helical device, such as a clamp, a micrometer, a ship's propeller or an Archimedes' screw water pump.


There is no universally accepted distinction between a screw and a bolt. A simple distinction that is often true, although not always, is that a bolt passes through a substrate and takes a nut on the other side, whereas a screw takes no nut because it threads directly into the substrate. Machinery's Handbook describes the distinction as follows:

ボルトは、組み立て部品の穴に挿入するために設計されたおねじ付きファスナーであり、通常、ナットにトルクを加えることで締めたり、外したりすることを目的としています。 ねじは、組み立て部品の穴に挿入したり、あらかじめ形成されためねじとかみ合ったり、それ自体のねじを形成したり、ヘッドにトルクを加えることによって締めたり、外したりできるおねじ付きファスナーです。 組み立て中の回転を防止し、ナットを締めるだけで締めたり外したりできるおねじ付きボルトはボルトです。 (例: 丸頭ボルト, トラックボルト、プラウボルト。)複数のピッチ長さの直線ねじをもつナットとの組み立てを禁止するねじ形状の雄ねじファスナーはねじです。 (例: 木ネジ, タッピングネジ。)[2]

この区別は、ASME B18.2.1と、ネジ[3] [4]およびボルトのいくつかの辞書定義と一致しています。[5] [6] [7]

The issue of what is a screw and what is a bolt is not completely resolved with Machinery's Handbook distinction, however, because of confounding terms, the ambiguous nature of some parts of the distinction, and usage variations.[8][not in citation given] Some of these issues are discussed below:

ASME standards specify a variety of "Machine Screws"[9] in diameters ranging up to 0.75 in (19.05 mm). These fasteners are often used with   Nuts  as well as driven into tapped holes. They might be considered a screw or a bolt based on the Machinery's Handbook distinction. In practice, they tend to be mostly available in smaller sizes and the smaller sizes are referred to as screws or less ambiguously as machine screws, although some kinds of machine screw can be referred to as stove bolts.

ASME規格B18.2.1-1996は、直径が0.25〜3インチ(6.35〜76.20 mm)の範囲の六角キャップスクリューを規定しています。 これらのファスナーはに非常に似ています 六角ボルト. They differ mostly in that they are manufactured to tighter tolerances than the corresponding bolts. Machinery's Handbook refers parenthetically to these fasteners as "Finished 六角ボルト".[10] Reasonably, these fasteners might be referred to as bolts, but based on the US government document Distinguishing Bolts from Screws, the US government might classify them as screws because of the tighter tolerance.[11] In 1991 responding to an influx of counterfeit fasteners Congress passed PL 101-592[12] "Fastener Quality Act" This resulted in the rewriting of specifications by the ASME B18 committee. B18.2.1[13] was re-written and as a result they eliminated the "Finished Hex Bolts" and renamed them the "Hex Cap Screw"-a term that had existed in common usage long before, but was now also being codified as an official name for the ASME B18 standard.

These terms refer to fasteners that are designed to be threaded into a tapped hole that is in part of the assembly and so based on the Machinery's Handbook distinction they would be screws. Here common terms are at variance with Machinery's Handbook distinction.[14][15]

ラグスクリュー(ラグボルトとも呼ばれますが、これは誤称です)は、基本的に大きな木ネジです。 角頭ラグねじと六角頭ラグねじはASME B18.2.1規格でカバーされており、通常、頭は外部六角です。 典型的なラグボルトは、直径が1⁄4インチ(6.35 mm)から1 1⁄4インチ(31.75 mm)、長さが1⁄4から6インチ(6.35から152.40 mm)以上で、粗いネジ山を使用できます。木ねじまたは板金ねじのねじ形状(大きい)。

材料は通常、亜鉛メッキ(耐食性)のコーティングが施された炭素鋼基板です。 亜鉛コーティングは、明るい(電気めっき)、黄色(電気めっき)、または亜鉛めっきされた鈍い灰色の溶融亜鉛めっきになります。 ラグボルトは、木材のフレームを一緒に遅らせたり、機械の足を木製の床に遅らせたり、その他の重い木工用途に使用されます。 形容詞の遅れは、そのようなファスナーの初期の主な使用から生じました:バレルのステーブや他の同様の部品などの遅れの固定。

These fasteners are "screws" according to the Machinery's Handbook criteria, and the obsolescent term "lag bolt" has been replaced by "lag screw" in the Handbook.[17] However, in the minds of many tradesmen, they are "bolts", simply because they are large, with hex or square heads. In the United Kingdom and Australia, lag screws are known as coach screws.

The US government made an effort to formalize the difference between a bolt and a screw because different tariffs apply to each.[18] The document seems to have no significant effect on common usage and does not eliminate the ambiguous nature of the distinction between screws and bolts for some threaded fasteners. The document also reflects (although it probably did not originate) significant confusion of terminology usage that differs between the legal/statutory/regulatory community and the fastener industry. The legal/statutory/regulatory wording uses the terms "coarse" and "fine" to refer to the tightness of the tolerance range, referring basically to "high-quality" or "low-quality", but this is a poor choice of terms, because those terms in the fastener industry have a different meaning (referring to the steepness of the helix's lead).

古いUSSおよびSAE規格では、キャップスクリューはシャンクがヘッドにねじ込まれたファスナーとして定義され、ボルトはシャンクが部分的にねじ込まれていないファスナーとして定義されていました。 このルールと定義によりボルトがナットをとるという考えとの関係は明らかです(グリップと呼ばれるシャンクのねじのない部分は、ねじ込まずに素材を通過することが期待されていたため)。 これは廃止された区別です。

The distinctions above are enforced in the controlled vocabulary of standards organizations. Nevertheless, there are sometimes differences between the controlled vocabulary and the natural language use of the words by machinists, auto mechanics and  Others . These differences reflect linguistic evolution shaped by the changing of technology over centuries. The words bolt and screw have both existed since before today's modern mix of fastener types existed, and the natural usage of those words has evolved retronymously in response to the technological change. (That is, the use of words as names for objects changes as the objects themselves change.) Non-threaded fasteners predominated until the advent of practical, inexpensive screw-cutting in the early 19th century. The basic meaning of the word screw has long involved the idea of a helical screw thread, but the Archimedes screw and the screw gimlet (like a corkscrew) preceded the fastener.

ボルトという言葉も非常に古い言葉であり、何世紀にもわたって基板を通過して反対側に固定される金属棒を指すために使用されました。多くの場合、ねじなしの手段(クリンチ、鍛造溶接、ピン留め、ウェッジなど)で固定されています。 )。 この感覚とドアボルトまたはクロスボウボルトの感覚との関連は明らかです。 19世紀には、ねじ山を介して締め付けられたボルトは、しばしばクレンチボルトとは対照的にねじボルトと呼ばれていました。

In common usage, the distinction (not rigorous) is often that screws are smaller than bolts, and that screws are generally tapered while bolts are not. For example, cylinder head bolts are called "bolts" (at least in North American usage) despite the fact that by some definitions they ought to be called "screws". Their size and their similarity to a bolt that would take a nut seem linguistically to overrule any other factors in this natural word choice proclivity.

Bolts have been defined as headed fasteners having external threads that meet an exacting, uniform bolt thread specification (such as ISO metric screw thread M, MJ, Unified Thread Standard UN, UNR, and UNJ) such that they can accept a non-tapered nut. Screws are then defined as headed, externally threaded fasteners that do not meet the above definition of bolts.[citation needed] These definitions of screw and bolt eliminate the ambiguity of the Machinery's handbook distinction. And it is for that reason, perhaps, that some people favor them. However, they are neither compliant with common usage of the two words nor are they compliant with formal specifications.

考えられる違いは、ねじはそれ自体のねじを切るように設計されていることです。 固定されているコンポーネントの反対側からアクセスしたり、露出したりする必要はありません。 このネジの定義は、ルーフクラッディング用のTekネジ、さまざまな金属製の留め具用のセルフドリルネジ、セルフタッピングネジ、ルーフバッテンネジとルーフバッテンボルトと垂木、デッキネジなど。一方、ボルトは、完全に同じねじ設計の事前に装備されたソケット(またはナット)で受け入れられるように設計されたファスナーシステムのオス部分です。

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