Method of thread machining
1. Thread grinding is mainly used to process the precision thread of hardened workpiece on thread

grinder. It can be divided into single line grinding wheel and multi line grinding wheel according to the

different section shape of grinding wheel.

The pitch accuracy of single line grinding wheel is grade 5 ~ 6, and the surface roughness is

r1.25 ~ 0.08 μ m. It is convenient for grinding wheel dressing. This method is suitable for grinding

precision lead screw, thread gauge, worm, small batch thread workpiece and shovel grinding

precision hob.

Multi line grinding wheel grinding is divided into longitudinal grinding method and cut in grinding

method.

The width of the grinding wheel in the longitudinal grinding method is less than the length of the

thread to be ground. The thread can be ground to the final size by moving the grinding wheel

longitudinally for one or several times.

The width of the grinding wheel in the cut in grinding method is greater than the length of the

thread to be ground. The grinding wheel cuts into the workpiece surface radially, and the workpiece

can be ground after about 1.25 revolutions. The productivity is high, but the precision is slightly low,

and the grinding wheel dressing is complex. The cut in grinding method is suitable for shoveling and

grinding large quantities of taps and grinding some threads for fastening.

2. Thread grinding is a nut type or screw type thread grinding tool made of soft materials such as cast

iron. The parts with pitch error on the machined thread on the workpiece are subject to forward and

reverse rotation grinding to improve the pitch accuracy. Hardened internal threads are usually ground

to eliminate deformation and improve accuracy.

3. Tapping and threading is to use a certain torque to screw the tap into the pre drilled bottom hole on

the workpiece to process the internal thread.
Threading is to cut out the external thread on the bar (or pipe) workpiece with a die. The machining

accuracy of tapping or threading depends on the accuracy of tap or die. Although there are many

methods to process internal and external threads, small-diameter internal threads can only be

processed by tap. Tapping and threading can be operated manually, or lathe, drilling machine, tapping

machine and threading machine.

4. Thread rolling is a processing method in which a forming rolling die is used to make the workpiece

produce plastic deformation to obtain threads. Thread rolling is generally carried out on a thread

rolling machine, a thread rolling machine or an automatic lathe attached with an automatic opening

and closing thread rolling head. It is suitable for mass production of external threads of standard

fasteners and other threaded connectors. The outer diameter of the rolled thread is generally no

more than 25mm, the length is no more than 100mm, the thread accuracy can reach grade 2

(gb197-63), and the diameter of the blank used is roughly equal to the pitch diameter of the

processed thread. Generally, the internal thread cannot be processed by rolling, but for the

workpiece with soft material, the slottless extrusion tap can be used to cold extrude the internal

thread (the maximum diameter can be about 30mm). The working principle is similar to tapping.

When cold extruding internal thread, the required torque is about twice larger than tapping, and

the machining accuracy and surface quality are slightly higher than tapping.
The advantages of thread rolling are:

① The surface roughness is less than that of turning, milling and grinding;

② The strength and hardness of the thread surface after rolling can be improved due to cold

work hardening;

③ High material utilization;

④ The productivity is doubled than that of cutting, and it is easy to realize automation;

⑤ Rolling die has a long service life. However, the hardness of workpiece material for rolling thread

shall not exceed hrc40; High requirements for blank dimensional accuracy; The precision and

hardness of rolling die are also high, so it is difficult to manufacture die; It is not suitable for rolling

threads with asymmetric tooth shape.

According to different rolling dies, thread rolling can be divided into thread rolling and thread rolling.

According to different rolling dies, thread rolling can be divided into thread rolling and thread rolling.
The thread rolling is that two thread thread rolling plates are staggered with 1 / 2 pitch, the static plate

is fixed, and the moving plate moves in a reciprocating straight line parallel to the static plate. When

the workpiece is sent between the two plates, the moving plate moves forward to rub and press the

workpiece to make its surface plastic deformation into threads.

There are three kinds of rolling wire: radial rolling wire, tangential rolling wire and rolling head

rolling wire.

① Radial thread rolling: two (or three) thread thread rolling wheels are installed on mutually parallel

shafts, the workpiece is placed on the support between the two wheels, the two wheels rotate at the

same speed in the same direction, and one wheel also makes radial feed movement. The workpiece

rotates driven by the thread roller, and the surface is extruded radially to form threads. For some

lead screws with low precision requirements, similar methods can also be used for rolling forming.

② Tangential wire rolling: also known as planetary wire rolling, the rolling tool is composed of a

rotating central wire rolling wheel and three fixed arc wire plates. During wire rolling, the workpiece

can be fed continuously, so the productivity is higher than that of wire rolling and radial wire rolling.

③ Thread rolling head: it is carried out on an automatic lathe and is generally used to process short

threads on workpieces. In the rolling head, there are 3 ~ 4 thread rollers evenly distributed around

the periphery of the workpiece. During thread rolling, the workpiece rotates and the rolling head feeds

axially to roll the workpiece out of the thread.

Furniture Leveling Feet Parameter

Furniture Leveling Feet Size

Furniture Leveling Feet Material

Furniture Leveling Feet Describe

Application.

Furniture Leveling Feet Scope of application

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