绝命毒师第四季
Lathe Construction. The esntial components of a lathe are depicted in the block diagram. The are the bed, headstock asmbly, tailstock asmbly, carriage asmbly, quick-change gear box, and the lea&crew and feed rod.
the artistThe bed is the backbone of a lathe. It usually is made of well-normalized or aged gray or nodular cast iron and provides a heavy, rigid frame on which all the other basic components are mounted. Two ts of parallel, longitudinal ways, inner and outer, are contained on the bed, usually on the upper side. Some makers u an inverted V-shape for all four ways, whereas others utilize one inverted V and one flat way in one or both ts. Becau veral other components are mounted and/or move on the ways they must be made with precision to assure accuracy of alignment. Similarly, proper precaution should be taken in operating a lathe to assure that the ways are not damaged. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed. The ways on most modem lathes are surface hardened to offer greater resistance to wear and abrasion.
个人陈述 英文The headstock is mounted in a fixed position on the inner ways at one end of the lathe bed. It provides a powered means of rotating the work at various speeds. It consists, esntially, of a hollow spindle, mounted in accurate bearings? And a t of transmission gears similar to a truck transmission through which the spindle can be rotated at a number of speeds. Most lathes provide from eight to eighteen speeds, usually in a geometric ratio, and on modem lathes all the speeds can be obtained merely by moving from two to four levers. An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives.
Becau the accuracy of a lathe is greatly dependent on the spindle, it is of heavy construction and mounted in heavy bearings, usually preloaded tapered roller or ball types, a longitudinal hole extends through the spindle so that long bar stock can be fed through it. The size of this hole is an important size dimension of a lathe becau it determines the maximum size of bar stock that can be machined when the material must be fed through the spinale.
The inner end of the spindle protrudes from the gear box and contains a means for mounting various types of chucks, face plates, and dog plates on it. Whereas small lathes often employ a threaded ction to which the chucks are screwed, most large lathes utilize either cam-lock or key-drive taper nos. The provide a large-diameter taper that assures the accurate alignment of the chuck, and a mechanism that permits the chuck or face plate to be locked or unlocked in position without the necessity of having to rotate the heavy attachments.
Power is supplied to the spindle by means of an electric motor through a V-belt or silent-chain drive. Most modem lathes have motors of from 5 to15 horpower to provide adequate power for carbide and ceramic tools at their high cutting speeds.
The tailstock asmbly consists, esntially, of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon, with a means for clamping the entire asmbly in any desired location. An upper casting fits on the lower one and can be moved transverly upon it on some type of keyed ways. This transver motion pemf
its aligning the tailstock and headstock spindles and provides a method of tuming tapers. The third major component of the asmbly is the tailstock quill. This is a hollow steel cylinder, usually about 2 to sinches in diameter, that can be moved veral inches longitudinally in and out of the upper casting by means of a handwheel and screw. The open end of the quill hole terminates in a mor. Taper in which a lathe center, or various tools such as drills, can be held. A graduated scale, veral inches in length, usually is engraved on the outside of the quill to aid in controlling its motion in and out of the upper casting. A locking device permits clamping the quill in any desired position.plz
The carriage asmbly provides the means for mounting and moving cutting tools. The carriage is a reianvely fiat H-shaped casting that rests and moves on the outer t of ways on the bed. The transver bar of the carriage contains ways on which the cross slide is mounted and can be moved by means of a feed screw that is controlled by a small handwheel and a graduated dial. Through the cross slide a means is provided for moving the lathe tool in the direction normal to the axis of rotation of the work.
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On most lathes the tool post actually is mounted on a compound rest. This consists of a ba, which is mounted on the cross slide so that it can be pivoted about a vertical axis, and an .upper casting. The upper casting is mounted on ways on this ba .so that it can be moved back and forth and controlled by means of a short lead screw operated by a handwheel and a calibrated dial.
