190 Каталог KYOCERA 2016 Твердосплавный вращающийся режущий инструмент ENG Стр.188

Catalog KYOCERA 2016 Solid carbide cutting tools Стр. 188 0190 ENG Lab2u

TAPS ENGINEERING DATA TERMS DEFINITIONS DEFINITION OF TERMS APPLYING TO TAPS ALLOWANCE Minimum clearance between two mating parts; the prescribed variations from the basic size. ANGLE OF THREAD The angle included between the sides of the thread measured in an axial plane. AXIS The imaginary straight line that forms the longitudinal center line of the tool or threaded part. BACK TAPER A gradual decrease in the diameter of the thread form on a tap from the chamfered end of the land towards the back which creates a slight radial relief in the threads. BASE OF THREAD The bottom section of the thread; the greatest section between the two adjacent roots. BASIC SIZE The theoretical or nominal standard size from which all variations are derived by application of allowances and tolerances. CHAMFER The tapering of the threads at the front end of each land of a tap by cutting away and relieving the crest of the first few teeth to distribute the cutting action over several teeth; Taper taps are chamfered 7-10 threads; plug taps are chamfered 3-5 threads; bottoming taps are chamfered 1-2 threads; taper pipe taps are chamfered 2-3.5 threads. CHAMFER RELIEF The gradual decrease in land height from cutting edge to heel on the chamfered portion, to provide clearance for the cutting action as the tap advances. CREST The top surface joining the two sides or flanks of the thread; the crest of an external thread is at its major diameter, while the crest of an internal thread is at its minor diameter. CUTTING FACE The leading side of the land in the direction of cutting rotation on which the chip forms. FLUTE The longitudinal channels formed in a tap to create cutting edges on the thread profile, and to provide chip spaces and cutting fluid passages. HEEL The edge of the land opposite the cutting edge. HEIGHT OF THREAD The distance, measured radially, between the crest and the base of a thread. HELIX ANGLE The angle made by the advance of the thread as it wraps around an imaginary cylinder. HOOK The undercut on the face of the teeth. HOOK ANGLE The inclination of a concave cutting face, usually specified either as Chordal Hook or Tangential Hook. Chordal Hook Angle: The angle between the chord passing through the root and crest of a thread form at the cutting face, and a radial line through the crest at the cutting edge. Tangential Hook Angle: The angle between a line tangent to a hook cutting face at the cutting edge and a radial line to the same point. INTERRUPTED THREAD TAP A tap having an odd number of lands with alternate teeth along the thread helix removed. In some cases alternate teeth are removed only for a portion of the thread length. LAND The part of the tap body which remains after the flutes are cut, and on which the threads are finally ground. The threaded section between the flutes of a tap. LEAD The axial distance a tap will advance along its axis in one complete turn. On a single start, the lead and the pitch are identical; on a double start, the lead is twice the pitch. MAJOR DIAMETER Commonly known as the “outside diameter.” It is the largest diameter of the thread. MINOR DIAMETER Commonly known as the “root diameter.” It is the smallest diameter of the thread. PERCENT OF THREAD One-half the difference between the basic major diameter and the actual minor diameter of an internal thread, divided by the basic thread height, expressed as a percentage. PITCH The distance from any point on a screw thread to a corresponding point on the next thread, measured parallel to the axis and on the same side of the axis. The pitch equals one divided by the number of threads per inch. 188 Kyocera