When boring treatment performance decreases, the reason can be caused by a specific factor or the result of the combined action of several factors. These factors include the stability of the part, the size of the machining allowance, the rigidity of the tool system, the grade of insertion and the geometry, the cutting speed and the performance of the correspondence tool the food frequency. When you meet situations such as long treatment cycle time, the lifespan of the shortened tool or the poor quality of the parties, these factors must be analyzed and identified.
In a particular boring process, the influence of a factor can be more significant than others, but these factors can also be closely linked to each other. The change in one of these factors can mean that to achieve the desired result, the other factor must be modified at the same time. However, do not change two or more factors at a time when performing cutting tests.
1. Stability of the part
Although the machining centers and the lights are generally not the first factor that can be taken into account in the machining workshop, if the part is unstable during machining, the machine-tool and the lights can also Seriously affect tool cutting performance.
If the tightening rigidity of the part is guaranteed, the size and power of the tool-tool will also affect the cutting settings. Although the machines with the conical bot50 bt50, BT40 and BT30 bores can use the same boring head, not all machines can finish the same boredom process. The same goes for the boring depth. On the BT50 machine, the holes with a 75 mm hole diameter and a 250-300 mm hole depth can be bored. that 40 does not support this treatment.
Used machine pins and unstable lights are often factors that cannot be changed but must be treated. Sometimes these factors can completely fail a machining task, but the generally modification of the type of insertion or the cutting parameters will provide a solution.
2. Processing indemnity
Processors often do not know how many margins should be reserved for boring treatment. Users can be more familiar with the cutting speed / the supply rate for turn machining and the machining allowance, but these experiences do not always apply to boredom. This is particularly true in noisy boredom using boring tools. It is not uncommon to have a forest diameter very close to the diameter of the final bore of the room (only a boring margin of 0.5 to 0.75 mm is left). Insert points of the boredom tool. If there is an insufficient machining allowance and tolerances of loose diameter (a minus ten thousand), it is better to use a boring tool (or the boredom tool that eliminates one of the insert children) .
On the other hand, for the parts with central holes, if the central hole is incorrect, there may be too much part of the piece to be cut. Even if the diameter of the core hole is in the standard beach typical of the rough bore margin, a bias in the nucleus can ensure that the bore tool takes a larger amount of cutter on one side From the hole that the blade can withstand the load of chip.
3. Rimidity of the assembly of tools
When selecting a boring tool for a machining task, it is generally based on the annoying diameter required and the nominal depth, with little consideration of the depth of real boredom and the additional overhang required (if necessary) . For example, in boring machining, the boring depth is only 50 mm, but the tool can reach the boredom length of 200 mm through the room and / or the pliers. This is very different from the boredom treatment required with a boring depth of 250 mm.
To maximize the rigidity of the tool and the range of use, a modular encouragement system can provide an unlimited number of module combinations. With the length of the required tool, it is important to first select a larger basic diameter of the bore bar, then reduce the diameter of the bore bar as needed, rather than adopt The same dimension of diameter throughout the length of the bore bar.
For a boring long overhang with a limited space, a full carbide bore bar can be envisaged (rather than several extensive stems). This configuration offers higher rigidity and better control, but is generally limited to boring treatment with smaller diameters.
For a long overhang, a modular boredom system which uses a larger connection size and reduces the diameter of the tool when necessary, has a more stable boredom system than a tool configuration which does not consider that the nominal bore length and the bore diameter.
4. Grade of blade and geometric shape
The blade is a key contact point between the part and the tool. If the insert does not correspond to boring treatment, even if the boredom tool system is extremely rigid and precisely balanced with the boring head, it can be difficult to obtain ideal machining performance.
If the blade geometry cannot guarantee cutting stability, it will be useless to use the best blade note. Boring inserts with pressed geometric shapes generally use a relatively conservative circuit breaker, which can maintain a long service life under stable treatment conditions, but their radial cutting depth should be at least 1/2 of the radius of the Arc de la Pointe. In certain hard bore processes (such as depth hole or long overhang, a long mosquito net of the chip material or an unstable tightening of the part caused by machine tools and / or accessories), grinding of inserts boring geometric can be more effective freely.
For a specific bore treatment, the notes and blade coatings used are constantly upgraded. When the boring steel pieces, the most commonly used are the grades of cermet and three layers. Disted carbide grades can also be used for cast iron boredom, and ceramic inserts of silicon nitride and certain grades of cubic boron nitride (CBN) can also be used for boring melting if the treatment conditions are stable. Aluminum and other non -ferrous metallic materials can be bored with non -covered carbide inserts, which generally have a broken chip -to -chip table with large positive angles to avoid long strips of chips. For the high -speed precision bore of these materials, inserts with points or polycrystalline diamond (PCD) coatings can also be a good choice. It should be remembered that the stability cut is the first requirement to extend the lifespan of the blade.
5. Distribute the speed and the power rate
Once all other factors are taken into account, it is also necessary to determine whether the cutting speed and the power speed are appropriate. These cutting parameters are essential to achieve optimal free cutting conditions. The annoying state ideal is to adopt a very high cutting speed and a relatively moderate power rate, but this can also be limited by the above conditions.
In a rough borehole with boring tools, a common error consists in simply multiplying the supply rate of a boring point at a single point by 2. This calculation method is generally not correct: for the treatment of the Boring with the same bore diameter, the power speed of the rough alternation tool can reach 4 times that of the fine work -study tool, because the rough alternation tool can adopt a radius of larger peak arc. For example, if the tip radius of the fine bore tool is 0.2 mm or 0.4 mm, the rough bore insert can adopt a 0.8 mm tip radius. The radius of the arc of the tip of the double tool, and with the use of two inserts, the supply frequency can reach 4 times that of the fine perception tool.
In general, the rough bore does not require a very fine surface finish, so a better rigid bore tool can be used to treat at a higher cut speed. If the food rate of the boredom tool is too small, it will cause floating due to an inappropriate machining allowance. The rough work -study tool is used for boredom with larger loads, which requires cutting more part materials and a higher power rate.
The processors sometimes find it difficult to determine the appropriate surface cutting speed for fine drilling. Optimization of cutting speed is essential to extend the life of the blade. If high load boredom is carried out at very high cutting speeds, a large amount of cutting heat will be generated and the lifespan of the insert will be shortened. Reducing flea load can reduce the cutting temperature, so the bore insert can be treated at a higher surface supply rate.
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