![]() ![]() When the thread forming tap is ground, as shown in FIG. The thread forming tap also comprises a plurality of oil grooves disposed in a circumferential direction of the thread forming tap. ![]() 6), and a parallel thread 102 which is formed continuously with the chamfer 101. 6, a conventional thread forming tap has a threaded portion 100 comprising a chamfer 101 which is tapered to form a complete mountain-like (angle) shape (see inclination angle in FIG. The present invention relates to a thread forming tap and a threading method.Īs shown in FIG. 9, 2000 including specification, claims, drawings and summary is incorporated herein by reference in its entirety. The entire disclosure of Japanese Patent Application No. A thread forming tap having a threaded portion comprising a tapered chamfer and a parallel threaded portion which is formed continuously with the chamfer, wherein a depth of a root of the chamfer is set equal to that of a root of the parallel threaded portion constantly. A threading method of a thread forming tap having a threaded portion comprising a tapered chamfer and a parallel threaded portion which is formed continuously with the chamfer, wherein after a parallel portion from the chamfer to the parallel threaded portion is continuously ground, a front flank to a rear flank of the chamfer are ground while alternately and gradually changing a feeding ratio between a tip end and a rear end of the chamfer and then, an outer diameter portion of the chamfer is ground.ģ. A threading method wherein a front flank and a rear flank of a thread are formed while alternately and gradually changing a feeding ratio between a tip end and a rear end of threaded portion and then, a parallel threaded portion is formed and thereafter, an outer diameter portion of the thread is ground.Ģ. Fine threads are recommended if two or more full thread engagements must be above the cutting slot, but the material is not thick enough to allow two full threads of coarse threads.1. Coarse threads should be used with weak materials. Tapping screws are available with either coarse or fine threads. Tapping screws are used in steel, aluminum, die-castings, cast iron, forgings, plastics, reinforced plastics, and resin-impregnated plywood. Taping screws are usually case hardened and have tensile strengths of at least 100,000 psi with relatively high ultimate torsional strengths. The close fit usually keeps the screws tight even when subject to vibrations. Mating threads created by these tapping screws fit the screw threads closely, and no clearance is needed. In general, tapping screws permit rapid insertion because nuts are not used and access is required from only one side of the joint. The screws are used in materials where disruptive internal stresses are not wanted, or when it takes to too much driving torque to use thread-forming screws. ![]() ![]() The screws’ cutting action means torque needed for insertion is low. Thread-tapping screws have cutting edges and chip cavities that create a mating thread by removing material from the part they are driven into. They usually do not need lockwashers or other types of locking devices to prevent loosening. Because no material is removed, the mating part creates a fit with zero clearance. These screws generally are used when large stresses are needed to increase resistance to loosening. The thread-forming screw displaced material around the pilot hole so that it flows around the screw’s threads. There are two basic types: thread forming and thread cutting. Tapping screws form mating threads in materials they are driven into. ![]()
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