With the improvement of people's living standards, people are more and more interested in things with metallic textures, which also makes aluminum products increasingly used in many industries. Aluminum processing industry in the country is generally nothing more than ordinary machine tools, carved machine and CNC machining center processing. Select machines for the precision of aluminum and aluminum alloys. Because of the special characteristics of aluminum, regardless of the processing machine used, the tool is often unsatisfactory in terms of efficiency and life-time workpiece gloss for the current aluminum production industry.
"The characteristics of aluminum are as follows: Relative to steel and superalloy, it is a soft metal, HRC hardness is not high, but it is more flexible, so the relative demand for the tool is higher, if the soft metal High-hardness tungsten steel cutters will cut off the blades, and the tool life is very short. It requires a low hardness, and does not stick to the knife's high-quality tools to complete the processing, the knife can only be so as to increase the speed of the machine In order to improve efficiency, according to Luo Baihui, the secretary-general of the International Mould and Metals and Plastics Industry Suppliers Association, the special aluminum end mills introduced by the brand division of Zhongshan Elan Precision Cutters Co., Ltd. adopt German high-quality bars and special features for aluminum. The design and grinding further solve problems such as burrs, non-brightness, and easy tool wear in the processing of aluminum materials and aluminum parts, and are dedicated to improving the gloss, precision, and efficiency of metal processing.
1, suitable for processing materials: aluminum and aluminum alloys, aluminum, aluminum die-casting parts, aluminum parts, copper alloys, magnesium alloys, zinc alloys 2, effectively remove the product around the glitches, Feng front problems, etc., with good processing quality.
3, the use of high rigidity knife body design, can inhibit vibration, so that the workpiece surface accuracy, good gloss.
3, the unique edge groove design, is conducive to the excretion of iron filings, so that the aluminum sheet light without burr.
4, negative rake angle blade, can inhibit blade edge chipping as a whole because the overall carbide cutting tool has a very sharp cutting edge and groove type, which in the aluminum alloy machining, cutting force is small, and has a large space chip spacing, row The advantages of smooth swarf and other advantages, so the overall carbide CNC tool gradually replaced the traditional high-speed steel tool.
In addition, the modulus of elasticity of cemented carbide is approximately 3 times that of steel, which means that the overall carbide tool deformation is only one-third that of the indexable tool under the same load. The solid carbide end mill can also be made into a spiral blade, so that it can smoothly cut in and cut out, and chip evacuation is also smooth and smooth, which helps to reduce the fluctuation of cutting force and thus suppress the resulting Vibration trend.
Indexable insert tooling systems offer potential advantages for aluminum roughing and finishing, especially when using medium to large diameter tools from 25 to 100 mm. The indexable end mills for aluminum alloy machining require no regrind, have better safety, versatility, and higher metal removal rates, providing unmatched performance. However, finishing in many cases cannot reach the required level. However, now Sandvik Coromant's CoroMill 790 can achieve this with new cutting edges, inserts, insert seats and clamping technology.
Improvements to CoroMill 790 When developing a new endmill concept for aluminum alloy machining, a key breakthrough in the use of indexable inserts for radial milling can be achieved by modifying a series of parameters. The main technical difficulties include: smooth cutting action; good chip formation; extremely high material removal rates; low power consumption; very good surface roughness and minimal knife-to-knife marks; ensuring tool safety at high speeds.
For machining of aluminum alloys, especially for finishing machining with small margins, indexable inserts often appear blunt, often resulting in “ploughing” effects. The cutting edge is also prone to slam into the workpiece, causing a sudden increase in cutting force. . A sudden increase in cutting force results in excessive knife and excessive power requirements. The above problems are further complicated due to the requirements of the cutting edge. A sharp positive rake cutting edge must be used for finishing. In order to ensure the metal removal rate during rough machining, the cutting edge is required to have sufficient strength. Therefore, considering cutting force, cutting edge cutting, chip formation, stability, and blade positioning and clamping, a new method is needed to use indexable inserts.
Cutting force on the cutting edge When the cutting edge of the milling tool cuts into the workpiece, a sudden impact will cause the tool to vibrate. The resulting cutting force mainly depends on the chip thickness, which is proportional to the feed rate. The initial induced tool vibration will change the subsequent chip thickness, which may then continue to increase as the cutting force changes, which in turn causes the processing system's vibration to increase. The direction and magnitude of the cutting force largely determine the vibration trend. This kind of regenerative vibration is also called flutter. If it is not suppressed, the variation of cutting force will increase, resulting in a decrease in the surface roughness after cutting, resulting in a knives, or even damage to the cutting edge and the tool. It has an adverse effect on the spindle of the machine tool.
For this reason, it is necessary to suppress the drastic variation of the cutting force at the start of cutting to suppress the tendency of vibration, which is also the main reason for using a vibration-proof tool. However, in many cases, this is achieved by optimizing the parameters of the blade structure. The establishment of a satisfactory model (which can accurately calculate and predict cutting forces) is one of the main basis for the development of new insert geometries. Subsequent advanced FEM simulations presented many answers concerning the combined design of edge lines, rake angles, and chip breakers as well as the development and optimization of new cutting edge features on the flank of the insert. This is based in large part on the vibration waveform calculated by the measured modal parameters.
The factors of the land are well known. When milling cast iron, the wear of the flank faces a certain degree of vibration damping. The flank wear area rubs against the machined surface and absorbs vibration energy, which results in attenuation of the amplitude. Logically, this effect should also be able to suppress other types of milling vibrations. The difficulty faced by this technology is how to reasonably use the specifically designed flank wear band as the main flank. In order to obtain the correct damping effect, its position on the blade, its angle, its width, and the range used on the cutting edge need to be quite accurate and should have the correct relationship with other design factors on the blade.
If this technique is applied properly, the buffering flank land edge can suppress the increase of the tool deformation, thus controlling the chip thickness and radial cutting force. The secret of Sandvik Coromant's patented new blade design is that when the blade has a tendency to deviate from the workpiece, its land will come into contact with the correspondingly formed machined surface on the workpiece at the moment the tool begins to bend backwards – thus Prevents increase of tool amplitude during machining. This means that the blade has a constant stabilizing effect, which is also part of the cutting action. The occasional brief contact between the specially designed primary backlash edge and the workpiece is very gentle and does not have any effect on tool cutting performance, wear development, or burr formation. As a result, the radial cutting force changes very little.
The key to the success of this technology is the size and position of the main rear corner land with respect to the blade geometry and tool diameter. The finite element analysis with the cutting process simulation is then used to evaluate the cutting force, chip formation, and distribution of stress levels in the insert.
The diameter of the factors for the impact of radial cutting force, small to medium-diameter tool rigidity is not easy, more prone to deflection, while large-diameter tools are relatively stable, and their anti-vibration requirements are not the same. In addition, it was found that the feed rate is not a major factor affecting the radial cutting force. The radial cutting force is only slightly different between different feeds of the tool (usually 0.25 mm and 0.35 mm per tooth feed). The change. For a typical 25-m-diameter aluminum alloy milling cutter, the cutting edge on the blade is 1°, 0.1 mm wide, and is perfectly matched to the curved cutting edge.
Aluminum alloy is a material with good machinability. Its material has a unit cutting force of approximately one-third of that of steel and a melting point of 625 degrees. This low melting point means that the cutting zone temperature will not exceed 625 degrees regardless of the cutting speed. Cemented carbide inserts can withstand very high temperatures without excessive wear and no effect on the strength of the cutting edge.
Higher cutting speeds require more power. In fact, a common problem in the high-speed machining of aluminum alloys is the need for large machine power, which tends to result in low metal removal rates per unit of power. Therefore, it is usually required that the machine tool can still provide the largest possible output power at high rotation speeds. In high-speed machining of aluminum alloys, it is very beneficial to reduce the required power due to the improvement of the tool.
From the tool point of view, the main cutting force has a decisive influence on the power demand. The power required to reduce the amount of removal per unit of material has a significant positive impact on the milling of aluminum alloys. The specific performance of each process is higher productivity, and the machining capacity of the machine is also stronger. In addition to determining whether cutting is light, the rake angle also affects the main cutting force. The new blade design minimizes cutting forces by increasing the rake angle while matching the rest of the blade geometry. The new CoroMill 790 blade design significantly reduces power requirements.
