MRCM share / 2022-01-20 / Hits(277)
Evaluation index of the service life of the MRCM twist drill grinder
What's wrong with drilling? Second question: chipping and chip removal
As the most common special tool in hole processing, twist drill is widely used in machinery and equipment manufacturing.
First, the characteristics of drilling
Drills generally have two critical cutting edges, which are produced while cutting. The larger the rake angle of the twist drill from the central axis to the outside, the faster the cutting speed and the faster the cutting speed. The twist drill is located on the periphery of the center line of the rotation center along the edge, with a large outer edge angle and a low cutting amount. When the cutting and grinding of din1414 is C-shaped, the cutting edge around the management center axis is a positive angle, which can reduce the cutting frictional resistance and improve the workability.
According to the appearance, material, structure and function of the product workpiece, drills can be divided into spring steel drills, rotatable shallow drills, deep drills, power socket drills and speed-adjustable drills.
2. Chip breaking and chip removal
The laser cutting drill is developed in a narrow hole in the indoor space, and the laser cutting drill must be discharged according to the concave groove of the drill. Common IC shapes include block IC, tube IC, needle IC, tapered spiral IC, strip IC, fan IC, powder IC, etc.
①The fine chips block the chisel groove, affect the accuracy of the drill bit, reduce the life of the drill bit, and then break the drill bit (powder chips, fan-shaped chips, etc.).
(2) The long chips are coiled around the drill bit, preventing the actual operation, causing the drill bit to break or preventing the cutting oil from entering the hole wall (such as spiral chips, strip-shaped chips, etc.). ).
In addition, the short-term iron market sales make it easier for coolant to be injected into the tip of the twist drill, further improving radiator cooling and production processing. In addition, because the newly added cutting edge penetrates all the grooves of the twist drill, the appearance and function can be maintained after several polishing. In addition to the improved effect, the design solution also improves the bending rigidity of the twist drill, which significantly increases the total number of twist drills before one repair.
3. Accuracy of twist drill
Diameter accuracy is mainly composed of diameter, position accuracy, parallelism, concentricity, roughness and burrs.
Elements that endanger punching accuracy:
Accuracy and drilling standards of twist drills, such as CNC blade pliers, cutting speed, passes, cutting oil, etc.
(2) The size and shape of the drill bit, such as the length of the drill bit, the shape of the edge, the shape of the core, etc.
③The shape of the product workpiece, such as the shape of the side of the filler, the shape of the filler, the thickness, the card installation situation, etc.
The expansion is caused by the shaking of the twist drill during production. The shaking of the CNC blade fixture is very harmful to the positioning accuracy of the hole and the hole. In the case of serious damage to the CNC blade fixture, a new CNC blade fixture should be replaced immediately. In the whole process of drilling, it is very difficult to accurately measure and adjust the shaking. Therefore, when using a thick-shank twist drill, the cutter head and the rocker have excellent coaxial output. When using a heavy-cut twist drill, because the reverse side looks different, resulting in twist Due to the decrease in drilling accuracy. By operating the stairs of the cutting edge, the exposure of the hole can be reasonably suppressed.
2 hole roundness
Because of the vibration of the twist drill, it is very easy to punch irregular patterns, and the edge of the hole looks complicated. The most common irregular pattern holes are triangular or pentagonal. The reason for the triangular hole is that the twist drill has 2 rotation centers, and each rotation center vibrates at a power switching frequency of 600. The vibration is mainly caused by the uneven friction of the twist drill. When the deep level of the drilling team reaches a certain level, the friction between the edge of the twist drill and the middle of the hole edge increases, the vibration attenuation coefficient, the composite profile subsides, and the concentricity increases. This type of hole is a Buchner funnel created by a vertical section. For the same reason, there will also be a reduction in the Pentagon and Heptagon. In order to clear this kind of situation, in addition to the vibration of the control collet, the height of the trimming, the asymmetry of the back and the appearance of the cutter head, we should also take measures to effectively improve the bending rigidity of the twist drill and increase the amount of material fed in each bend. , Reduce the clearance angle, repair the cross-blade.
Drill holes in skewed floor plans and surface layers
When the cutting edge or drill face is skewed, the surface layer or the stairs, the accuracy level is weak.
In order to improve the positioning accuracy, the following precautions must be taken
①Drill the center hole first.
②. Mill the hole seat with an end mill.
③Choose a drill with good penetration and rigidity.
④ Decrease the feed rate.
4 Glitch processing
In punching, burrs appear in the passages and entrances and exits of the holes, especially when producing and processing raw materials and sheets with high ductility. The reason is that when the drill bit is going to drill through, the material is plastically deformed. When a triangular member that should be laser cut by a rim edge perimeter drill is subjected to radial cutting speed effects, the triangular portion of the drill bends outward.
Fourth, the processing conditions of drilling
In the general catalogue of twist drills, based on the raw materials for production and processing, a reference table for basic drilling quantities is compiled. According to factors such as machining accuracy, high production and processing efficiency, and service life of twist drills, the cutting standard is selected according to tool radius compensation.
1. Drill life and processing efficiency
Under the premise of taking into account the standard specification of the workpiece of the commodity product, the appropriate use of the drill should be considered according to the application cycle time and high efficiency. The selection of the whole drilling process can select the evaluation index of the twist drill's service life, and can select the evaluation index of the high efficiency of production and processing according to the cutting speed. For spring steel drills, the service life of the drill is affected by the speed ratio and the feed per revolution in many ways. Therefore, increasing the feed per revolution and long life can improve the efficiency of production and processing. As everyone knows, it should be noted that if the cutting speed of each circle is large, the cutting will become thick, making the cutting unable to be crushed. Therefore, it is necessary to clarify the range of the cutting speed per revolution according to the trial cutting, so that the cutting can be completely crushed. For carbide tool drills, the rake angle of drilling has a large rounding angle, and the selectable range of each feed is lower than that of spring steel drills. Because the temperature resistance of the carbide drill is higher than that of the spring steel drill, the speed ratio is not harmful to the service life of the drill. If you want to learn UG programming, you can find some teachers learning CNC numerical control technology.
2 Reasonable use of cutting fluid
The drill bit is drilled into the small round hole in the indoor space, so the type and introduction method of the cutting fluid have a great impact on the service life and machining accuracy of the drill bit. Cutting fluids can be divided into water-soluble and water-insoluble. The waterless cutting oil has excellent wetting, adhesion, anti-adhesion and its anti-rust treatment to solve practical effects. Water-soluble cutting oil has excellent refrigeration, smoke control, and no flammability. In recent years, water-soluble cutting fluids have been widely used in the environmental protection industry. However, if the dilution ratio of the water-soluble cutting fluid is not good or the cutting fluid is moldy, the service life of the CNC blade will be greatly shortened, so be careful. Whether it is water-soluble or non-water-soluble cutting fluid, the cutting fluid must reach the drilling point completely in the application. In addition, be sure to strictly control the total flow of cutting fluid, working pressure, total number of nozzles and cooling method (internal cooling or external cooling).
5. Re-sharpening the drill
Drill bit regrinding
The specifications for re-sharpening twist drills are:
The cutting edge is damaged, the cutting edge is damaged;
(2) The specification accuracy and surface roughness of the production and processing holes;
③ The color and shape of the chips;
Cutting resistors (or indirect values such as spindle bearing current, noise, vibration, etc.);
⑤ Processing quantity, etc.
In specific applications, precise and convenient specifications need to be clarified from the index values. When using the amount of wear as a rule, the best damage cycle time should be identified. Because the key cutting components are the reverse and lateral edges of the head, such as twist drills with high wear rate, long cutting time and large cutting amount, the frequency of regrinding can be reduced (total service life of CNC inserts, regrind CNC inserts The service life of the CNC blade after regrinding, the overall service life of the twist drill, etc. Once the straight hole specification is applied.
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