Twin-screw extruder thread tapping 1. Taps and reamed taps Taps are forming tools used to process smaller diameter internal threads. They are generally made of alloy tool steel 9SiGr and are made by heat treatment. become. Each tap consists of a working part and a shank. The working part is composed of cutting part and calibration part. There are several chip flutes in the axial direction, correspondingly forming several blades and rake angles. The cutting part is an important part of thread cutting and is often ground into a conical shape so that the cutting load can be distributed among several teeth. The cone angle of the head cone is smaller, and the cone angle of the second cone is larger. The calibration part has complete teeth, which are used to smooth the thread and guide the tap to move along the axial direction. The handle has a square head, and its function is to cooperate with the hinge and transmit torque. The hinge is a tool used to hold the tap, and the commonly used one is the adjustable hinge. The size of the square hole can be adjusted by turning the handle to accommodate taps of different sizes. The length of the hinge should be selected according to the size of the tap to control the torque when tapping and prevent the tap from being twisted due to improper force application. 2. Determine the diameter and depth of the drilled bottom hole before tapping the thread of the twin-screw extruder, and determine the diameter of the bottom hole for chamfering the hole. During the thread tapping process, the cutting edge of the tap mainly cuts metal, but there is also extrusion. The effect of pressing the metal causes the metal to bulge and flow toward the tooth tips. Therefore, before tapping the thread, the diameter of the drilled hole should be larger than the inner diameter of the thread. The diameter of the bottom hole can be checked in the manual or when tapping the thread of a blind hole. Since the tap cannot tap to the bottom, the depth of the hole must be greater than the length of the thread. The depth of the blind hole can be chamfered before tapping the thread. , to facilitate the positioning and cutting of the tap. The depth of the chamfer is greater than the pitch of the thread. 3. The key points and precautions for the operation of twin-screw extruder thread tapping should be based on the specifications of the threaded holes on the workpiece. Select the tap correctly, with the first taper first and the second taper second. Do not use it upside down. When clamping the workpiece, make sure the center of the hole is perpendicular to the jaws to prevent the thread from being twisted. At the same time, no more pressure can be applied to prevent the tap from chipping or the tapped thread teeth to be thinner. When tapping internal threads on steel parts, add machine oil to lubricate them, which can make the threads smooth, save labor and extend the service life of the tap; tap internal threads on cast iron without adding lubricant, or add kerosene; tap internal threads on aluminum, aluminum alloys, and copper Thread, emulsion can be added. Do not blow chips directly with your mouth to prevent them from flying into your eyes.
2. Twin-screw extruder thread sleeve thread
1. Die and die frame. The die is a tool for processing external threads. It is made of alloy tool steel. The outer circle of the die has a deep strip. Groove and four taper pits, the taper pits are used to position and fasten the die. Twin-screw extruder thread die holder
The die holder is a tool used to clamp the die and transmit torque. Dies with different outer diameters should use different die frames. Determination of the diameter of the round rod and the diameter of the chamfered round rod before threading
Same as tapping, there is a cutting effect when threading, 3. Operation points and precautions for threading before threading each time The chips in the die flutes and threads should be cleared. Before threading, check the diameter of the round rod and the end chamfer. When threading, the cutting torque is very large, which can easily damage the machined surface of the round rod, so hardwood should be used. Use a V-groove liner or a thick copper plate as a protective sheet to clamp the workpiece. The length of the workpiece extending out of the jaws should be as short as possible without affecting the required thread length.