| 释义 |
▪ I. countersink, n.|ˈkaʊntəsɪŋk|
[f. next.]
1. A tool for countersinking: see the verb.
1816J. Smith Panorama Sc. & Art I. 115 The head of the countersink is conical. 1849Weale Dict. Terms 124 Countersinks for iron have two cutting edges forming an obtuse angle.
2. The conical enlargement of the upper part of a hole for receiving the head of a screw or bolt. Cf. countersunk n. Hence countersink bit, a bit for cutting a countersink.
1846Worcester cites Tanner. 1869E. J. Reed Shipbuild. xvii. 330 The shank is conically shaped under the head in order to fit the countersink. 1879Cassell's Techn. Educ. IV. 135/2 Punching..has..the advantage of giving a slight countersink, or conical form to the hole.
▪ II. countersink, v.|ˌkaʊntəˈsɪŋk|
Pa. tense and pple. countersunk.
[counter-, app. in a sense akin to 8 b, the hole being the counterpart of that which is to be sunk in it.]
1. trans. To enlarge the upper part of (a hole or cavity), usually into a conical form, to receive the head of a screw, bolt, etc.; to bevel the edge of a hole.
1831J. Holland Manuf. Metal I. 170 The practice of countersinking the holes, to receive the nail heads. 1861Wynter Soc. Bees 189 Counter-sinking the eyes in order that they may not cut the cotton. 1869E. J. Reed Shipbuild. xxi. 482 The holes in the plates to receive the bolt-heads are countersunk one-half through the plates.
2. To sink the head of (a screw, bolt, etc.) in a depression made to receive it, so that it lies flush with the surface.
1816J. Smith Panorama Sc. & Art I. 70 The heads of the bolts must not project above the surface of the plate; therefore the grooves must be..wider at the top than the bottom, and the heads may then be countersunk. 1868Regul. & Ord. Army §573 b, The horse's shoe is not to be grooved but simply punched, and the nails countersunk.
Hence ˈcountersinker, a tool for countersinking; = countersink n. 1; ˈcountersinking vbl. n.
1881Mechanic §319 The rose or roundheaded countersinker. 1888Daily News 25 Apr. 6/1 Countersinking machines. |