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Causes and prevention measures of metal surface roughness defects

Views: 0     Author: Site Editor     Publish Time: 2022-05-09      Origin: Site

Cross shaft double universal joint shafts: causes and prevention measures of metal surface roughness defects

1. Analysis of common roughness defects

1) Rough analysis of knife marks

Rough defect is generally reflected in the increase of cutting feed, mainly because in the cutting process, due to the shape of the tool makes part of the metal machining surface is not removed, residual in the machining surface, called the knife mark.

2) Scaly sting phenomenon

Generally in the cutting speed is low, and the use of high speed steel or hard alloy cutting tool on plastic metal material cutting, easy to appear on the surface of the scaly crack and burr, this phenomenon is called scaly phenomenon.

Generally in broaching, cutting, hobbing and other processing process is prone to this situation. When in the low speed, small rake cutting plastic materials, will form the situation of extrusion chip, which causes the role of the force between the knife and chip, and periodically change, which makes the metal accumulation, processing surface fracture and scaly phenomenon.

3) Scratches and hairpulling

Scratches and hair-pulling are also common in the roughness defect category. Gnawing phenomenon in gear processing and hair-pulling in grinding process are representative phenomena of scratches and hair-pulling. And we can be based on scratches and traces of hair, the cause of their analysis, in order to develop good elimination measures.

4) The knife is uneven

In view of the phenomenon of uneven cutter, the main reason lies in the machine tool, the main performance is the metal surface of the tool cutting mark is not uniform.

5) high frequency vibration marks

In the process of metal processing, the whole process system will vibrate accordingly, and machine tools, cutters and workpiece will have a great influence on the surface roughness of metal parts. The low frequency vibration of the process system generally produces ripple degree on the workpiece surface, while the vibration pattern produced by the high frequency vibration of the process system belongs to the category of roughness.

The vibration of process system mainly includes forced vibration and self-excited vibration. Forced vibration is caused by the action of periodic external forces. The self-excited vibration is the vibration excited by the system movement itself, and the most common self-excited vibration is the cutting vibration.

2. Exclusion analysis of common roughness defects

1)  Analysis of knife mark elimination

First of all, when cutting, we should choose a smaller feed within the allowable range, but the feed can not be too small,single single universal joint half shaft manufacturer - Xinsanming otherwise it will affect the roughness of cutting. Secondly, when grinding the tool, the radius of the tip arc should be appropriately increased within the allowable range, which will have certain benefits to the roughness.

2)  Elimination analysis of scaly sting phenomenon

The first is to control the cutting speed. The scaling phenomenon is partly due to the cutting speed, beyond or below a specific speed range, scaling phenomenon will occur.

Second is the cutting thickness, to minimize the cutting thickness, the increase of cutting thickness, for chip and the pressure between the tool front will be more and more large, if the formation of extrusion chip or unit chip, will make the scale thorn phenomenon more frequent and serious.

In addition, the cutting fluid of good quality can effectively restrain the scaling phenomenon. Reasonable selection of tool Angle is also an effective method to eliminate the scaly phenomenon.

Finally, the cutting machinability of the workpiece material is constantly improved. For example, in some cases, the material can be heated and then cut, so that the phenomenon of scale thorns will be reduced.

3)  Elimination analysis of scratches and hair

Scratch and hair if the trace distribution is more regular, generally because of the machine tool problems, machine tools such as spindle box, slide board box, feed box and other traditional systems in the shaft bending, gear teeth bad or damage, will appear regular scratch and hair phenomenon, so it is necessary to regularly check the machine tool, often maintenance.

If there is an irregular distribution of scratches and hair-pulling marks, it may be related to chips, tools, or cutting fluids. For example, in the process of deep hole processing, poor chip removal will cause scratches on the inner surface. Workpiece surface hair, generally in the grinding process due to abrasive particles, abrasive chips fall off, may also be improper grinding wheel, cutting fluid is not clean, so it is necessary to choose the appropriate grinding wheel and clean cutting fluid.

4)  Elimination analysis of knife flower irregularity

There are many reasons for uneven cutters, but the most common ones are linear helical marks on the surface of parts when grinding outer circles. This is caused by the large straightness error of grinding wheel bus, which requires us to do a good job regularly in the selection and maintenance of grinding wheel. In addition, for example, the machine tool workbench or tool rest crawling, will also cause uneven knife, so the maintenance of machine tools must be done, in order to prevent and avoid to the greatest extent.

5) Elimination analysis of high-frequency vibration marks

The main method to eliminate the high frequency vibration is to find the vibration source, eliminate the vibration, or reduce the vibration to the allowable range.

Through the research and analysis of common roughness defects in lathe processing, to find out the factors affecting the surface roughness in cutting, and find out the corresponding measures and elimination methods, on the one hand, it can prevent in advance before processing, on the other hand, it can find out the cause of the problem in time and accurately, and solve it in time. It has practical significance to improve product quality and promote interchangeability production.

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  : +86 29 86033971
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  : The Innovation Industrial Park, No.36, Jingwei Road ,Xi'an Economic and Technological Development Zone,Xi'an City,Shaanxi Province,China
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