TRAPEZOIDAL THREAD TAPS

 

Trapezoidal Thread taps are used for translational motion in machine tools like the lead squares where rapid movement is required. They usually come with trapezoidal outlines and they are the most common form of screw threads used for power tools. The trapezoidal thread tap have a flank angle of 30 degrees and they are considered to be stronger than the screw threads because the square thread taps have a smaller thread and thus cannot carry as many loads as the trapezoidal thread taps. Also, the single point cutting tools or taps that are used to cut the thread cannot have an efficient rake and relief angles due to the square shape of the square thread tap which makes cutting slow and difficult. 

A cross-section of the trapezoidal tap corresponds to an isosceles trapezoid with an angle of 15 degrees that eventually result in the tools having a flank angle of 30 degrees. The trapezoidal thread taps come in different standard sizes and are ready to install with corresponding nuts. The trapezoidal thread taps are best used in the applications listed below:

– They are best used as a multi-start trapezoidal screw that transforms smaller radial movement into large axial movement. 

– They are also used for conveying and squeezing materials in screw conveyors, screw pumps or injection molding machines. 

– They are also used as a power screw or lifting screws in heavy lifting operations that are combined with a load and safety nuts. 

– They are used as lead squares for transmitting motion and power in machine tools. 

– They are also used as feed screws in laboratory and life sciences equipment. 

Trapezoidal thread taps are manufactured on thread milling machine employing the use of multi-point cutting tools and the use of multi-point cutting tools is economical compared to that of the single point cutting tools. This calls for the low cost of trapezoidal thread tap. The axial wear on the surface of trapezoidal Thread taps can be compensated by means of a split type of nut that is cut into two parts along the diameter. This split type nuts are used only for trapezoidal Threads to compensate wear at periodic intervals by tightening the two halves. 

There are some features associated with this power tools and they are as follows:

  1. The Pitch: This is the distance measured parallel to the axis of the trapezoidal Thread taps from a point on one thread to the corresponding thread on the adjacent thread. 
  2. The Lead: This is the distance measured parallel to the axis of the screw thread that the advancement of the nut will be in one revolution of the screw. 
  3. Core Diameter: It is also known as the minor diameter and it is the smallest diameter of the screw thread. 
  4. Nominal Diameter: This is also called the major diameter and it is the largest diameter of the screw. 
  5. Lead Angle: It is the angle made by the helix of the thread with a plane perpendicular to the axis of the screw. 

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