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Wear and Its Influencing Factors of Diamond Tools for Hard and Brittle Materials
Author: yisainuo Time: 2017-05-27 18:18:17
1. introduction
With the development of science and technology and the development of modern industry, hard and brittle materials (such as laser and infrared optical crystals, ceramics, quartz glass, silicon crystal and stone, etc.) is increasingly widely used. As the hard and brittle material hardness, brittleness, its physical and mechanical properties
Especially toughness and strength compared with metal materials are very different, so these materials are difficult or even can not use ordinary processing methods for processing. Diamond is known to the nature of the highest hardness of the material, its excellent performance in the hard and brittle materials
Processing field has broad prospects. At present, the use of diamond tools for hard and brittle materials for cutting and grinding is still an effective processing methods, such as cutting tools with diamond cutting stone, grinding wheels with diamond grinding wheel.
Diamond tools with hard and brittle materials are mainly used in a variety of diamond saws and diamond wheels, etc., although the scope of application of various tools and processing characteristics are different, but the wear mechanism are roughly the same. Because the diamond tool wear on the workpiece processing quality
And the impact of the processing process is very large, the tool wear performance is to reflect the tool performance, process parameters are reasonable an important indicator, so the diamond tool wear mechanism to guide the diamond tool reasonable manufacturing and process parameters reasonable
Choice is of great importance. For a long time, many scholars at home and abroad are committed to the diamond tool wear mechanism research, and has made gratifying results.
2. Study on Wear Mechanism of Diamond Tools
When machining hard and brittle materials with diamond tools, the tool will inevitably produce wear due to severe friction, high temperature, etc., and wear is a very complicated process.
(1) the three stages of wear
The abrasion of diamond tools consists of three phases: the initial rapid wear stage (also known as the transition phase), the wear rate is about a constant wear stage and the subsequent accelerated wear stage. Accelerated wear stage indicates that the tool can not continue to work and is needed
Re-dressing.
(2) abrasive wear form
Abrasive wear can be divided into: the whole abrasive, micro-crushed abrasive, macroscopic crushing abrasive, abrasive off and abrasive grinding. The proportion of these types of wear is determined by the different wear stages, the tools used and the material to be processed. T W Liao and so on
The wear of the diamond grinding wheel in the micro - feed grinding ceramic structure is studied quantitatively. It is pointed out that the wear of the grinding wheel is different in the transition stage and the stable wear stage. The wear of the transition phase depends not only on the specifications of the grinding wheel, the material properties and the grinding conditions,
To the decision of the grinding wheel. In the transitional stage, because the grinding wheel has just been trimmed, the abrasive grains protrude the largest, and many abrasive grains do not participate in the cutting, so the proportion of the whole abrasive grains is higher than the stable stage; at the same time, the dressing makes many abrasive grains out too large,
Not enough, the proportion of abrasive particles fall off more than the stable stage; In addition, the dressing will weaken some abrasive particles, so that the proportion of micro-crushed abrasive grain than the stable stage. Steady grain abrasive wear is mainly friction and wear, the proportion of low micro-crushed abrasive grains and relatively high
Friction and wear ratio shows that the wheel does not appear from the sharp phenomenon, which is detrimental to the processing. Harbin Institute of Engineering, such as Qiu Zhongjun grinding wheel with diamond grinding ceramic, pointed out that the wear and tear of the grinding wheel is mainly abrasive wear and abrasive off. S Y LUO on King Kong
It is pointed out that the failure of the saw blade is mainly due to the macroscopic crushing and / or abrasion of the abrasive grains. When the number of abrasive grains is broken and the number of particles is more than 1/3, the tool fails. Huaqiao University in the Yuqing, etc. through the cutting stone,
Concrete and other materials in the process of diamond tool surface diamond and binder state of a large number of tracking observation and SEM analysis shows that: the overall abrasive to keep longer, easier to process, the higher the wear resistance of the tool; macro broken state will lead to diamond
The cutting edge height is significantly reduced, and even lose the cutting capacity; tools for a long period of time after cutting, abrasive natural wear blunt, the blade height reduction, with the abrasive particles around the further wear, the diamond's holding force weakened, causing the diamond off
drop. Xu Xipeng and other research saw the granite block when the diamond block wear, that the actual wear and tear process to go through different paths: from the complete crystal form, through micro-crushing and then to the macro broken, and finally fall off; can also begin to happen
Fall off. This depends on the quality of the diamond, the load and the binding agent and other factors. And the wear process of the metal bonding agent used in the diamond holding carrier has more complicated tribological properties. Granite chips and diamond debris in cutting fluid
Driven by the erosion of the surface of the binder, in its surface to form erosion traces, the binding agent in a similar fluid grinding conditions were abrasive. The crescent pits in the front of the diamond show that the fluid forms cavitation during the sawing process and causes erosion. In addition, the binder also
Grinding and plowing of hard spots in granite is similar to that of metal grinding.
(3) diamond tool wear mechanism
Diamond wear mechanism of the tools are roughly the following: friction and wear, abrasive particles broken, bonding agent crushing, abrasion wear, surface fatigue and shock, friction and wear so that abrasive grinding blunt and polished, Abrasion wear due
Weakened the strength of the binder to promote the abrasive particles off. Different wear and tear of the processing mechanism is different, such as: with diamond grinding wheel micro-feed grinding ceramic structure, the diamond grinding wheel wear mainly in three forms: friction and wear, abrasive wear
Crushing and bonding agents are broken; in addition, another form of wear is a binder abrasion. Yiyang Zhou with ceramic binder grinding wheel grinding sapphire, that the ceramic binder grinding wheel wear is mainly binding agent brittle fracture, and metal and resin
The grinding wheel wear is mainly abrasive and abrasive. The authors of the literature [5] cut the granite by cutting the diamond with a diamond saw blade, pointing out that there are four main wear mechanisms: friction and wear, abrasion wear, surface fatigue and impact. Xu Xipeng and other research saws
Cut the granite when the diamond block wear, that the diamond in the direct friction and wear with the granite at the same time, but also by the granite cutting debris impact and corrosion, the wear type can be attributed to: abrasive wear, impact Wear and fluid in solid
Body particles caused by erosion. X P XU and so on. The results show that the abrasive grain is mainly caused by the impact force, but the temperature change is also important because it can cause thermal fatigue damage and thermal stress.
3. Factors that affect the wear of diamond tools
(1) Tools
Diamond grade, content, particle size, bonding agent and diamond matching and tool shape and other factors associated with the tool itself is an important factor affecting the tool wear.
Usually diamond content is low, power consumption is also low; but the diamond content is too low, the macro crushing will increase, resulting in insufficient blade edge, so that increased power; diamond content is high, then increased power consumption, leading to diamond off, Grinding
But fell. If the diamond grade is higher, in the lower content of the case, its complete crystal rate is still high, block wear resistance, low power consumption, but the diamond grade should be matched with the choice of binder. Wu Jian et al. Analyzed the quality of diamond dispersal on sawing
The impact of the process, pointed out that high-quality diamond wear resistance, must require the binder also has a good wear resistance, the only way to give full play to the role of high-quality diamond. While for low-quality diamonds, due to their compression and impact resistance are
Poor, even when cutting the mineral composition easier to occur when the more obvious wear and tear, in the face of particularly difficult to cut part of the general will be macroscopic crushing and loss of cutting capacity, at this time on the bonding agent wear resistance requirements Should be relatively low,
To ensure that the diamond has a sufficient edge height. The literature [10] also pointed out that the quality of the diamond should be reduced. [8] by analyzing the ceramic binder diamond grinding wheel processing sapphire process in the spindle deformation (with the deformation of the mill
The change of the normal load required for the cutting of the binder is found to be cyclical, indicating that the grinding wheel has a sharpness because the wear of the ceramic binder grinding wheel is a brittle fracture of the binder material and a new abrasive grain is rapidly present. While metal and resin
The grinding wheel of the binder is mainly friction and wear and abrasion. Y C Fu et al gives the optimization model of grinding wheel grinding. Through this model, the grinding wheel can be optimized according to the processing requirements and grinding parameters (including abrasive grain size, concentration, extension rate and effective abrasive grain
Of the space), can also be based on grinding wheel and processing requirements to optimize grinding parameters (including grinding depth, wheel speed and workpiece feed rate). In addition, many scholars have carried out this research.
(2) processing conditions
As the diamond tool wear and its load state is closely related, so the processing conditions will have a significant impact on wear and tear. Dai Xiangguo and other analysis of the diamond grinding wheel engineering ceramic parameters on the wheel life of the impact of that when the other parameters of a
There is an optimum feed rate when the cutting depth and the grinding wheel speed are constant. The order of the influence of each process parameter on the radial wear of the grinding wheel is: the grinding wheel speed - Cutting depth -
Feed rate. [17] pointed out that the tool wear and processing parameters and processing parameters between the coordination of a great relationship, it is necessary to optimize the process parameters. Z J Pei analyzed the situation when the wafer was refined, and reached the following conclusion:
Grinding wheel speed of 4350rpm, chuck speed of 590rpm, the grinding force gradually increased, when reached a certain peak, it returned to a lower value, and continue to press this cycle, indicating that the grinding wheel gradually blunt, when the grinding force to a certain When the abrasive grain broken; when the wheel
Speed of 2175rpm, chuck speed of 40rpm, the grinding wheel in the grinding force is small when broken. Therefore, the grinding force is basically constant and the wear rate is high.
(3) processed material
Different parts of the material, the fracture toughness, hardness and other differences are large, so the nature of the workpiece material also affects the wear of diamond tools. [19] studied the use of diamond saws cutting different stone tools when the wear and pointed out: when the cutting hard
Of the granite, the diamond saws are mainly abrasive wear and fall off, because the grip is not enough, cutting conditions are bad; when cutting the soft granite, the complete crystal shape and abrasive micro-broken accounted for A larger proportion, while abrasive off
The proportion of falling is still high, this wear so that the blade to maintain cutting capacity. Xu Xipeng that: granite in the nature of different minerals and deformation mechanism is the key to determine the failure of the diamond. The higher the quartz content, the more intense the diamond wear;
If the content of the stone is obviously high, the sawing process is relatively difficult. Under the same sawing conditions, the coarse granite is more difficult to decompose than the grain granite.