What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Code name and standard number of inch thread commonly used abroad Mark code name country and standard number Remarks BSW standard Wyeth coarse thread series, general purpose cylindrical thread British standard BS 84 inch thread with a profile angle of 55° BSF standard Wyeth fine thread series, General Purpose Cylindrical Thread Whit.S Additional Whit.S Optional Series, General Purpose Cylindrical Thread Whit Non-standard thread with Whitworth profile UN Uniform thread of constant pitch series American standard ANSI B1.1 inch thread with 60° profile angle, with Internal and external threads with standard profile (flat or rounded at random) UNC Coarse thread unified thread UNF fine thread unified thread UNEF superfine thread unified thread UNS① Special series unified thread UNR round The uniform thread profile angle of the arc root constant pitch series is 60° inch thread, UNR, UNRC, UNRF, UNREF, UNRS with arc root are only used for external thread without internal thread UNRC arc root coarse thread Series Unified Thread UNRF Circular Root Fine Thread Series Unified Thread UNREF Circular Root Ultra Fine Thread Series Unified Thread UNRS Circular Root Special Series Unified Thread NPT② Generally used for pipe thread American standard ANSI B1.20.1 Profile angle is 60° Inch Pipe Thread NPSC Pipe Fitting Straight Pipe NPTR Pilot Connection Tapered Pipe NPSM Mechanical Connection Straight Pipe NPSL Lock Nut Straight Pipe NPSH Hose Connection Straight Pipe NPTF Dry Seal Standard Tapered Pipe Thread American Standard ANSI B1.20.3 Type I PTF-SAE SHORT Dry Seal Short Taper Pipe Thread Type II NPSF Dry Seal Standard Fuel Oil Straight Pipe Internal Thread III Type NPS1 Dry Seal Standard General Straight Pipe Internal Thread IV Type ACME③ General Purpose Trapezoid Thread American standard ANSI B1.5 Inch drive thread with 29° profile angle ① Dimensions and tolerances All diameter and pitch combinations other than the standard series are calculated using the same formula as the standard series. ② my country's 60° conical pipe thread GB/T12716-1991 is equivalent to it. ③ACME thread includes two kinds of matching trapezoidal threads, general purpose and centering, of which the general purpose thread has the same performance as the trapezoidal thread specified in my country's standard GB/T5796-1986.
new type of screw includes a fixing object and a screw body composed of a nut, a fixing piece and a screw rod. An outer gear ring is fixedly sleeved on the fixing piece, and a support plate is arranged on the lower side of the outer gear ring. The upper side of the support plate is connected with a mounting frame through an adjustment mechanism, the inside of the mounting frame is connected with the outer gear ring through an anti-drop mechanism, and a mounting plate is fixedly connected to the side of the support plate close to the fixed object, and the mounting plate is clamped The coupling mechanism is connected to the fixture.
The technical problem to be solved by Yueluo is to provide a medical self-locking screw, which can fix the inner screw inside the outer screw, expand the outer screw head through the thimble on the inner screw, and use the outer cone on the inner screw. The body expands, compresses the surrounding bone, and achieves a double locking effect through the self-locking between the internal and external screws; it can hook the surrounding fixed parts when the anti-retraction ring is retracted to achieve the anti-regression effect; effectively prevent false implantation. After a long period of service, the looseness, fretting and other adverse reactions of the body are used to solve the defects caused by the existing technology.
When checking the finished blind rivet, check: the diameter of the rivet body, the length of the rivet body, the thickness of the rivet body cap, the diameter of the cap, the total length of the mandrel, the exposed size of the mandrel, the size of the nail cap, and the outer diameter after assembly can be considered. In the actual inspection, the weak links of the product can be measured, such as: tensile force, shear resistance, and core pull-out resistance. The key is to pay attention to the rivets, if the rivets are insufficient, whether they are riveted in place; or because the cap of the mandrel is too large, so that the mouth of the rivet body cannot be pulled down; and there are jump heads, that is, the mandrel is too low or broken. The size is too small etc. Length measurement of closed blind rivets
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