Type of tap
Different by drive: hand tap and machine tap
According to the processing method: cutting wire tapping and extrusion tap
According to the thread to be processed: metric coarse wire tapping metric fine wire tapping, pipe thread tap, etc.
According to its shape, it is divided into straight groove tapping, spiral groove tapping and edge dip tap, extrusion tap
Straight groove tap
↠downward shavings
feature
Straight groove, high tip strength
Easy to select cutting cone length → 1.5·5·9 teeth
Easy to grind
Corresponding to the thread size
use
In high-hardness processing materials, materials that are prone to tool wear, through-holes with short tapping depths have good effects: (rigid rigidity)
The cutting cone portion can have 2, 4, and 6 teeth for non-through holes and long cones for through holes. As long as the bottom hole is deep enough, you should try to use a larger number of teeth that share the cutting load and have a longer service life.
Blade angle tap
↠downward shavings
feature
Blade pitch groove
Chip removal
Chips are not easy to entangle
High resistance to breakage
Good cutting performance
use
The chip is easy to form a curled material and can only be used for through holes.
Spiral grooved wire (through holes can also be machined)
Upward chip removal →
feature
Spiral groove
Can be machined to the bottom of a blind hole
No residual chips
Easy threading
Good cutting performance
use
Chips are curled
Blind hole;
Extrusion tap
Plastic deformation without chipping
feature
Plastic deformation without debris
Threading by plastic deformation of metal
No chips
Good internal thread accuracy
Anti-breakage
The top of the thread forms a groove,
Inset, different from cutting tap
Bottom hole management is strict
Large processing torque
use
Good ductility (low aluminum alloy, medium carbon steel) blind hole and through hole
The threaded hole processed by the extrusion forming process has high tensile strength and good roughness of the machined surface.
The difference between cutting taps and grooveless taps
Type of tap
Thread shape
The size of the bottom hole The shape of the thread The size of the bottom hole is, for example, the case of M8X 1.25J2
Bottom hole bottom hole tolerance
Cutting tap
Bottom hole size of JIS2
6.65~6.91
0.26
Extrusion tap
The bottom hole is approximately 1/2 pitch larger than the above size
7.34~7.41 is probably about the above size NRT 1/4~1/3
0.07
Simple calculation method for bottom hole: cutting tap: outer diameter pitch (the larger the bottom hole, the longer the tap life) the grooveless tap (extrusion tap): outer diameter - 1/2 pitch
Blind hole threading
The role of the groove on the cutting tap
Tap processing characteristics
Taps can be mass-produced, so the price is cheaper.
Tapping is easy and does not require skill.
It is easy to tap on a workpiece of complex shape.
Mechanical or manual tapping can be used.
Difficulties in tap processing
First, the problem of cutting taps
Grinding of the cutting cone
Bit grinding offset
Swing and feed are not synchronized
The tap turns too fast and too slow
Two: the problem of extrusion taps
Bottom hole requirements are strict;
Cutting taps above four points
The main reason for the stoppage is that the rotation and feed are not synchronized (simply, whether it is a floating chuck, the program, the machine tool rigid spindle screw has a direct relationship
Frequently encountered problems and countermeasures in tap processing
Tap break
Tapping
The reason for the sticky knife (melting)
Boring, biting reasons
Inappropriate tap model
Viscose knife for cutting part length (for example, soft steel SU304, aluminum)
Surface treatment, improper angle of tap, cutting fluid, oil filling method
Chip clogging (processing depth)
Internal boring
Under what conditions?
Improvement measures, tap selection is not appropriate
model
Improve cutting performance
Reduce friction heat
Surface treatment application
Improve chip discharge performance
Improved bottom hole diameter when the tapping condition is poor
Improve feed speed
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