be small at both ends and big in the middle;a few at each extreme and many in between

pin-to-pin reducer

两头阳螺纹的大小头

double pin sucker rod

两头阳螺纹的抽油杆

female-male reducer

两端分别带有内外螺纹的大小头

pepe bend with male and female thread

一头带阳螺纹一头带阴螺纹的弯头

pipe bend with female thread

两头带阴螺纹的弯头

male and female cross

阳螺纹-阴螺纹十字接头

A pipe coupling threaded on both ends.

螺纹接头一种两端都带外螺纹的管子

lead nipple for tubes or pipes

铅螺纹接头,用于大小管的

Hexagonal head shoulder screw with adjustable shoulder and thread sizes.

肩和螺纹大小可调整的六角头带肩螺钉。

box up and pin down

上部阴螺纹-下部阳螺纹接头

NC machining nut with large lead and 3-start rectangular thread

大导程三头矩形螺纹螺母的数控加工

Screwed 1;Screwed 2;Screwed 3;Screwed 4

螺纹接头 1;螺纹接头 2;螺纹接头 3;螺纹接头 4

Screwed Joint 1;Screwed Joint 2;Screwed Joint 3

螺纹接头 1;螺纹接头 2;螺纹接头 3

A small block of metal or wood with a central, threaded hole that is designed to fit around and secure a bolt or screw.

螺母，螺帽中部有螺纹用于与螺栓或螺钉相配合的小块金属或木头

tapped and plugged

车出螺纹用堵头堵上的

double-screw bolt

螺柱，双头螺纹螺栓

the part of a bolt between the thread and the head.

螺钉的头部和螺纹之间的部分。

Side view of fillister head slotted screw with adjustable thread length.

螺纹长度可调整的槽头螺钉的侧面图。