[Please check] The most comprehensive glitch problem analysis

article abstract

In recent years, in the passenger car powertrain industry where the author is located, the importance of the cleanliness of the whole product is increasing day by day. Although the focus of cleanliness work is the control of incoming material cleanliness and assembly process cleanliness control, in the field of machining, the burrs on the machined parts that have the risk of falling off are also an important hidden danger that affects the cleanliness of the whole machine.

Therefore, as machining engineers, we need to find a way to reduce the flanging burrs during the machining process. Previously, the author summarized the burr problems and countermeasures in the face of hole processing and surface processing. Faced with more and more glitch problems with different forms and sources, the author realizes that it is necessary to trace the root cause and mechanism of the glitch problem, and systematically explore solutions from the mechanism.

Therefore, the author will combine the relevant literature and his own work summary, divide the content into several issues, and explain in detail the source and countermeasures of the flanging burr problem of machined parts. Stay tuned. Above, right when the belated opening remarks of the cleanliness topic

1.The definition of burr

Burrs refer to the irregular metal parts such as various sharp corners and burrs that appear at the transition of the workpiece surface in metal processing. Deformed metal on a machined surface.

Most of what machining engineers face is the burr that occurs during metal cutting. Burr is one of the most common phenomena in the process of metal cutting, and it is also one of the two major problems that have not been solved so far in the theoretical research of metal cutting: the generation and control of burr, and the processing and control of chips.

2.The hazard of burrs

Burrs exist in the machining edges, corners, edges or machined surfaces of the workpiece, which directly affect the dimensional accuracy, shape and position accuracy and surface roughness of the workpiece to be machined, making it difficult to assemble the workpiece and meet the tolerance requirements. The hardening and shedding of burrs on parts is the source of crack initiation, so burrs can also reduce the service life of the workpiece, or even cause its operation failure, jeopardizing the safety of operators.

It has a great impact on the processing quality of the parts and subsequent assembly and use, and the deburring process is time-consuming and labor-intensive, which is one of the biggest obstacles to the entire cutting process and automated production lines.

In the processing of powertrain aluminum parts, burrs have become the most important problem affecting product cleanliness. Aluminum alloy materials have good plasticity and ductility, and burr problems exist in various cutting processes such as face milling, boring, and drilling.

In terms of product quality: after the burr falls into the engine lubrication system, it may cause problems such as wear of moving parts, sticking, and even locking of the crankshaft.

3. The formation of burrs

During the machining of the part, under the action of the cutting force of the cutting tool, such as a milling cutter, a drill, etc., plastic deformation occurs in the machining area of the part, so that the end material is separated from the original cutting path, resulting in the occurrence of two adjacent parts beyond the part. The material at the interface of the surface is called burr.

The shape and size of the burr produced by cutting depends on the comprehensive effect of various influencing factors such as material properties and process parameters. The relevant experimental research shows that the size and shape of the cutting burr mainly depends on the workpiece material and the support stiffness of the end, cutting The magnitude of the force and the direction of the cutting motion, etc.

The removal of burrs results in a substantial increase in labor costs and tool costs. Therefore, as machining process engineers, we strive to remove burrs during machining.

At present, the processes and methods for burr removal are quite limited, and there is no fundamental solution. The problems such as the generation mechanism of burrs, influencing factors, and how to effectively curb the generation of burrs or control the size of burrs need to be deeply analyzed and studied.

4.The removal of burrs

Burr removal methods are divided into: passive deburring, active deburring

1. Passive deburring

After the tool processing is completed, the methods of "contamination first, treatment later" such as brushing, high-pressure washing, and secondary processing are used. This method needs to formulate a corresponding process path according to the position where the burr is generated, and it is difficult to realize the burr in a special position.

Disadvantages of passive deburring

Ø Limited by the size and location of the workpiece to be processed.

Ø Introduce defects and introduce shape and position errors.

Ø Hardening the surface, introducing new factors that affect the surface quality of the workpiece.4

The current automatic deburring process still cannot achieve fully automatic operation. The passive deburring process is time-consuming and labor-intensive, and is the bottleneck of the entire automated production.

2. Active deburring

With the development of processing technology, more and more people are beginning to realize the harmfulness of burrs in the processing process, and it is urgent to change this passive situation, and then the concept of active deburring is proposed.

The idea of active deburring is to minimize or even avoid the generation of burrs during the processing process, and reduce or even cancel the subsequent deburring process, so as to achieve the purpose of reducing processing costs and improving workpiece quality.

By optimizing the tool structure, cutting parameters, process paths, etc., the size and shape of burrs are not generated or actively controlled during cutting, so as to improve the process environment for subsequent passive deburring.

Chapter summary

As a post-supplement to the topic of cleanliness, this article introduces the definition, hazards, formation and removal methods of burr problems from the basic concepts. Later, we will introduce the methods of burr removal according to different processing characteristics. Please pay attention to "Cleanliness Issues, EOS Theory of Milling Burr Removal" Reference: Luo Meng "Research on Burr Formation Mechanism and Control Method in Metal Cutting Process".