How to choose a suitable thread rolling machine for rolling high precision work-piece

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Author : Mandy Lau
Update time : 2019-12-02 18:04:24
     How to choose a suitable thread rolling machine for rolling high precision work-piece?
There are mainly four factors affect the precision of rolling work-pieces,including the stability of the machine, the accuracy of the rolling die, the choice of blanks, and the machine debugging. This paper mainly analyzes the stability of the machine.

About the machine stability,there are two important factors,transmission system and feeding system.We all know that the work-piece is formed by cold extrusion,the right roller moves forward to press the work-piece with the left roller,which is only rotating and not moving. The rotation of the roller is controlled by the main motor decelerating through the gearbox or worm gearbox, and then the shaft of the roller seat is connected through the transmission shaft to rotate.The feeding is controlled by the hydraulic system.Through the system,the hydraulic cylinder set on the slide pushes the right roller seat forward . Therefore, the stability of the transmission system and the feeding system ensure the stability of the machine.

Part One-the transmission system needs to be stable,which can be listed as follow.

1.Stability of the transmission mode. At present, there are two modes of transmission, worm gearbox transmission and gearbox transmission. The worm gearbox is single-speed driving,high transmission rate,and easily slow down.At the beginning,it’s fine,but for long term running,it will have worm damaged and big gap to affect the precision.The Gearbox is multi-speed driving, the force is stable, and the gap is not easy to occur. So the gear box transmission is more stable,longer lifetime,maintaining stable accuracy for a long time,but price will be little higher.Good thread rolling machines are normally driven by gearbox.

2.The connection between the gear box and the roller seat is connected through the transmission shaft, and the transmission must be stable without gaps. The key lies in the high precision of universal joints and the small gap of splines. Therefore, the selection of the transmission shaft is very important. A good transmission shaft makes the transmission without any jumping and stable when the gearbox transmit to the roller seat,so that the roller seat can ensure the precision of rollers.In a whole, when choosing a thread rolling machine, we must pay attention to the quality of the drive shaft.

3.The roller seat needs to be high precision,the left and right brackets are parallel to each other,which are at the same level. The accuracy can also be tested by rotating the circle motion of the spindle .As shown in the table below, there are five parts of testing. In the same range of rolling pressure, the spindle precision tolerance of TOBEST is higher than the market standard.

Part two-the feeding system of the machine should be stable, which can be listed as follows.

1.The stability of the feeding system the feeding and retraction are fully controlled by hydraulic,which is stable and make the positioning accurate to ensure the rolling accuracy of the work-piece. The integrated hydraulic system feed is more stable and less noisy.The split hydraulic system is easily shaking to lose stability.

2.The stability of the hydraulic oil cooling system  
At first,the oil is cool and will get hot after the machine running for a while.The volume of the liquid will expands to affect the feeding precision.According to the principle of thermal expansion and contraction,it will affect the precision of the feeding position when the oil is too high or too cold. For example, in cold area,it is necessary to warm up the machine before threading. Therefore, machines with hydraulic oil cooling system is much better.It can keep the oil temperature between 19℃ ~ 20℃.

3.The stability of the slide, without any loosing 
 The dovetail type,T-shaped and linear guide slide.The stability of the slide determines the stability of the feeding.Linear guide slide is normally used in is light lathe machine.And traditional thread rolling machine is heavy cold extrusion machine,so it’
s not suitable to use linear guide slide.T-shaped slide is easy to process and repair,it moves forward or backward through two boards locked by screws.The dovetail slide moves forward and backward as a unit.T-shaped slide easily has big gap and affect the precision for long term running,while the dovetail type slide has high force, high stability and high precision. So the dovetail type slide has higher stability than the T-shaped slide.

In addition to the influence of the transmission system and the feeding system, the cooling system of the coolant will also affect the accuracy of the work-piece. The coolant can promote the oil circulation and maintain a certain oil temperature. The iron powder generated by the work-piece can be filtered to avoid damaging the rollers and affecting accuracy.

There are still many factors affecting the precision of rolling work-pieces, please pay close attention to our homepage for more sharing! If you have other suggestions for this article, please leave a message to discuss.

Technical Consultant:Fuxin Hong      Technical Reviewer:Yi Lau