絲攻和絲板

絲攻和絲板（螺絲攻和螺絲板或螺攻和螺模），分別是用來製造螺旋內孔（螺母）和螺旋外周（螺絲）、以力矩旋轉方式作固定的工具。它們多數以工具鋼製成，並用於金工範圍。兩者均需要絲攻扳手 (Tap wrench) 的輔助來增加力矩。

絲攻（或稱螺絲攻或螺攻），「螺絲紋攻出器」之意。其外型好像有著螺絲坑紋的鑽嘴般，用以在（事前已經鑽好的）孔內製造雌性絲母形的絲紋。絲攻的「攻擊部份」並非為全圓形，而是留了等份的圓形弧坑道，方便攻出絲紋的工件部份的碎屑能夠從之移動，以免卡於絲紋隙縫中，阻止攻絲的繼續或使絲紋崩裂。

它們亦應適合的攻絲深度而分成三種：



1.錐頭絲攻：有著錐形的端頭，適合在孔口的起始部份應用，以錐形斜面壓向內孔邊緣，削走所需物料，減低兩者摩擦的阻力。（若果尖錐端頭強攻孔底而頂著，有機會引致中間的絲紋遭錯誤攻出。）

2.梯頭絲攻：端頭為梯形，適合在內孔中段全段使用。

3.平頭絲攻：單純的平頭，適合在內孔底部使用，好讓整個所需攻絲的深度都得以加工。（若果在孔口使用此形狀的絲攻，會產生絲紋螺旋軸心的角度誤差，而且進入亦非常因難，可能會刮花工件孔邊。）

它們由工具鋼的中身至端頭都刻有絲紋，另一頂端則是供絲攻扳手固定的固定形狀。

絲板（或稱螺絲板、絲模或螺板），是環形板狀的工具，用以在柱狀工件的周邊曲面上製造雄性螺絲形的絲紋。其內圓有效加工部份亦非為全圓形，同樣預留了圓形弧坑道，讓碎屑有流動空間。
 
 
 
 
資料來源:wiki百科


Taps and dies are cutting tools used when creating screw threads. A tap is used to cut the female portion of the mating pair (e.g. a nut). A die is used to cut the male portion of the mating pair (e.g. a bolt). The process of cutting the threads in a hole is called "tapping" the hole. The process of cutting with a die is called "threading" (or sometimes "chasing", although "chasing" is most commonly used when threads are already present but need to be "cleaned up").


A tap cuts a thread on the inside surface of a hole, creating a female surface which functions like a nut. The three taps in the image illustrate the basic types commonly used by most machinists:


1.Bottoming tap or plug tap:The tap illustrated in the top of the image has a continuous cutting edge with almost no taper — between 1 and 1.5 threads of taper is typical.This feature enables a bottoming tap to cut threads to the bottom of a blind hole. A bottoming tap is usually used to cut threads in a hole that has already been partially threaded using one of the more tapered types of tap; the tapered end ("tap chamfer") of a bottoming tap is too short to successfully start into an unthreaded hole. In the US they are commonly known as bottoming taps, but in Australia and Britain they are also known as plug taps.

2.Intermediate tap, second tap,or plug tap:The tap illustrated in the middle of the image has tapered cutting edges, which assist in aligning and starting the tap into an untapped hole. The number of tapered threads typically ranges from 3 to 5. Plug taps are the most commonly used type of tap.[citation needed] In the US they are commonly known as plug taps, whereas in Australia and Britain they are commonly known as second taps.

3.Taper tap: The small tap illustrated at the bottom of the image is similar to a plug tap but has a more pronounced taper to the cutting edges. This feature gives the taper tap a very gradual cutting action that is less aggressive than that of the plug tap. The number of tapered threads typically ranges from 8 to 10. A taper tap is most often used when the material to be tapped is difficult to work (e.g., alloy steel) or the tap is of a very small diameter and thus prone to breakage.


The above illustrated taps are generally referred to as hand taps, since they are, by design, intended to be manually operated. During operation, it is necessary with a hand tap to periodically reverse rotation to break the chip formed during the cutting process, thus preventing an effect called "crowding" that may cause breakage. Periodic reversing is usually not practical when power tapping is involved, and thus has led to the development of taps suitable for continuous rotation in the cutting direction.


The most common type of power driven tap is the "spiral point" plug tap (also referred to as a "gun tap"), whose cutting edges are angularly displaced relative to the tap centerline. This feature causes the tap to continuously break the chip and eject it into the flutes, preventing crowding. Another version of the spiral point plug tap is the spiral flute tap, whose flutes resemble those of a twist drill. Spiral flute taps are widely used in high speed, automatic tapping operations due to their ability to work well in blind holes.

Whether manual or automatic, the processing of tapping begins with forming and slightly countersinking a hole (usually by drilling) with a diameter somewhat smaller than the tap's diameter. The correct hole diameter may be determined by consulting a drill and tap size chart, a standard reference item found in many machine shops. If the hole is to be drilled, the proper diameter is called the tap drill size.

In lieu of a tap drill chart, it is possible with inch sized taps to compute the correct tap drill diameter as follows:

where TD is the tap drill size, MD is the major diameter of the tap (e.g., ⅜ inch for a ⅜"-16 tap), and N is the number of threads per inch ( 16 in the case of a ⅜"-16 tap). For a ⅜"-16 tap, the above formula would produce 5⁄16 as a result, which is the correct tap drill diameter for a ⅜"-16 tap. The result produces a tap drill size that results in an approximate 75 percent thread.

With soft or average hardness materials, such as plastic, aluminum or carbon steel, the common practice is to use a plug tap to cut the threads. If the threads are to extend to the bottom of a blind hole, the plug tap will be used to cut threads until the point of the tap reaches bottom, after which a bottoming tap will be used to finish the hole. Frequent ejection of the chips must be made in such an operation to avoid jamming and possibly breaking the tap.

With hard materials, the machinist may start with a taper tap, whose less severe diameter transition reduces the amount of torque required to cut the threads. If threads are to be cut to the bottom of a blind hole, the taper tap will be followed by an intermediate (plug) tap and then a bottoming tap to finish the operation.

In metal working, the use of a tap lubricant is essential to achieve cleanly formed threads and to minimize friction. Failure to use the correct lubricant may result in ragged threads, as well as a substantial increase in the amount of torque required to turn the tap, possibly resulting in breakage.


information by wiki.

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