Abstract In recent years, as the automobile manufacturing industry has entered a stage of rapid development, diversification and personalization have become the main features of its development. At the same time, automobile and gearbox manufacturers such as engines and gearboxes have also placed more urgent demands on efficient processing. Tools as the main influence on processing efficiency...
In recent years, as the automobile manufacturing industry has entered a stage of rapid development, diversification and personalization have become the main features of its development. At the same time, automobile and gearbox manufacturers such as engines and gearboxes have also placed more urgent demands on efficient processing.
As the main factor affecting the processing efficiency, the tool has received more and more attention, and the tool supplier has been continuously optimized in terms of tool materials and structure.
——The author of this article is Beijing Jinwanzhong Technology Development Co., Ltd. Liu Chaoyang
In metal processing, efficient machining is the eternal pursuit of all manufacturing companies, including tool manufacturers. In recent years, as the automobile manufacturing industry has entered a stage of rapid development, diversification and personalization have become the main features of its development, and improving the ability of automobile manufacturers to respond quickly to changes in market demand is an important means of winning competition. At the same time, auto parts manufacturers such as engines and gearboxes have also placed more pressing demands on efficient machining.
Machine tools, tooling, crafts and even programming software, cutting fluids, etc. all affect machining efficiency, but the most important components of machining are: machine tools, tooling and tools. Among them, the tool plays the role of finally cutting the material, which is an important factor that can achieve high-efficiency machining. In particular, the tool has the option of using the limits of existing production equipment and shortening the machining time by means of tools, which has a direct driving effect on achieving efficient machining. The old saying goes, "If a worker wants to do something good, he must first sharpen his weapon." Today, it is given a broader connotation in modern manufacturing. To improve machining efficiency and continually optimize the “tool” – the tool is very important. Here are a few ways to optimize the tool.
"Lee" its material, changing the cutting speed
Tool suppliers have been continuously developing and introducing tools with longer life and faster cutting speeds to achieve higher feed rates and improved machining efficiency. To change the cutting speed, the key is to change the base material and surface coating of the cutting material. At present, tool suppliers' choice of tool materials mainly focuses on hard alloys and some CBNs, and has continuously increased research and development efforts to introduce new products, taking the tool materials introduced by Sumitomo Corporation of Japan as an example:
For the cutting of general carbon steel and alloy steel, the cutting speed of early cemented carbide coating material is V=100～250m/min, and Sumitomo's new material AC700G/AC820P is processed through the technological innovation of base metal and coating. The cutting speed has been increased to V=390m/min for the SCM420 drive shaft. At the same time, it has excellent resistance to breakage. When machining SCM425 gears, it can achieve a cutting depth of 5mm, and the feed rate is 0.5mm/rev, which is 1.5~2.7 times of the service life of the original material.
For hardened steel (HRC58~62) material products, such as bearings, shaft keys and gears, most of them are processed by grinding before heat treatment, and the efficiency is low and the size is not easy to guarantee. Some users also use CBN (cubic boron nitride) material processing, but the cutting speed is low (80 ~ 150m / min), processing efficiency and surface quality is not high. The new material BNC100 from Sumitomo has a cutting speed of 100 to 300 m/min and a feed rate of 0.1 to 0.35 mm/rev while maintaining high line speed. Similarly, in automotive mold milling, the BN700 material round-blade milling cutter developed by Sumitomo Co., Ltd., together with the BRC arbor, can achieve 150-400 m/min when SKD is quenched to HRC47-52 material and NAK pre-hardened steel HRC40-45 material. And ultra-high speed finishing of 200 to 800 m/min, the processing time is shortened by 3 to 5 times, and the surface finish is excellent.
"profit" its structure, changing the cutting allowance and feed of the tool
The structure of “Li” mainly refers to the continuous optimization of the structure of the cutter body and the geometric design of the insert, and the new breakthrough in processing efficiency from the aspects of improving cutting force, cutting edge mode and strength, taking Japanese BIG (Dazhaohe) and Sumitomo products as examples:
1. FCM fast peak milling cutter
BIG has a double rake angle design with 20° axial rake angle and large radial rake angle on the milling cutter. It not only cuts lightly, but also has low resistance. At the same time, it applies the eccentric relief technology to the machine clamp vertical milling for the first time. On the knives, the back angle is not too large, which does not affect the sharpness of the blade, but also improves the blade strength and is not easy to chip.
For example, on the BT40 spindle machine, the S50C material is cut, the φ32mm milling cutter has a cutting depth of 9mm, the speed is 1500r/min, and the feed can reach 550mm/min. Due to the light cutting speed and the good right angle and beautiful wall surface after processing, the straight angle can be 0.01mm and the roughness Ra is 0.51mm. This product not only achieves a breakthrough in efficiency in conventional slot milling and square shoulder milling, but also enables efficient machining in situations where the spindle power is insufficient, the clamping rigidity is poor, and the suspension depth is long.
2. EWB-UP high speed super precision hoe
The primary feature of the fine boring head is the adjustment accuracy and machining accuracy. Since the fine boring head is single-edged, it is impossible to achieve high-speed and efficient machining. BIG combines the dimensional accuracy adjustment and the offset equalization dynamic balance adjustment into one boring part. The adjustment accuracy of 0.001mm and the dynamic balance factor G6.3 at the highest speed are easily achieved by two dial rotations. . With diamond and CBN materials, aluminum alloy parts (such as gearbox housing) and cast iron cylinder bore products can be processed at high speed and high efficiency of 200-2000m/min, and good processing results are obtained.
3. Non-standard composite structure tool
For a large number of products with complex structures, numerous processes and difficult to machine, standard tools are no longer able to meet the requirements of efficient machining. This requires a more targeted design of the tool structure based on specific parts, effectively reducing tool change time. Sumitomo's special tools for the machining of crankshafts and camshaft bores of automobile engines, including broaches, valve seat milling cutters, and automatic guide boring tools, are typical products for non-standard tools to promote efficient machining development.
"Li" clamping, achieving high cutting speed and high feed
The tool holder clamping system is the connection between the machine tool spindle and the tool. It carries the precision and rigidity of the spindle and the rigidity of the tool holder. The dynamic balance, clamping force and clamping accuracy are the necessary conditions for high-speed and efficient machining. . Take BIG products as an example:
1. High speed and high precision clamping shank
For cutting tools with a diameter of φ20mm or less, especially for small-diameter cutting tools with a diameter of 0.25 to 12mm, high-efficiency, high-precision machining and excellent surface finish are required to achieve high-speed machining, which is the accuracy and dynamic balance of the shank. Performance indicators present more stringent grade requirements. BIG's beauty gripper series has a clamping port runout accuracy of 0.001mm, a 4x diameter front runout accuracy of 0.003mm, and a jacket accuracy grade of AA. The handles are processed by dynamic balance test, and the maximum speed can reach 40 000r. /min, and standard configuration center water, fully meet the requirements of high-speed high-precision drilling, reaming and milling. The φ8.5×5D drilling hole of the aluminum alloy cylinder product is processed, and the OSG hard alloy coated drill bit FTO-GDS is used after the US shank is used. The processing parameters are n=6000r/min, f=0.45mm/rev, The efficiency is increased by 3 to 4 times. At the same time, the aperture accuracy is effectively guaranteed.
2. Heavy-duty strong grip holder
This type of shank is mainly for φ20～50mm large diameter cutting tools. Since this diameter range is in the rough machining category, it has higher requirements on the rigidity and clamping force of the shank. BIG's HMC powerful tool holder series features a unique slit mechanism, thickened grip, good rigidity and 300Nm of super torque. BIG's other BBT beauty clip high-speed double-handle series can meet the needs of high-speed and powerful cutting, and the clamping accuracy is between 0.005 and 0.01mm. If it is matched with the BBT main shaft, the shank taper surface and the flange end face can be closely fitted with each other, and the rigidity can be enhanced by 3 to 4 times, achieving strong and efficient re-cutting, and obtaining a good deep hole processing effect.
Conclusion
In the field of automotive processing, especially in the mass production process, the accuracy, cutting speed and life of the tool directly affect the starting rate of the production line, the processing cycle, and even the final production efficiency. According to the survey, nearly 70% of the cost of tooling costs in China accounts for 2% to 3% of the total cost of production. Although the ratio is not very high, the selection of reliable, applicable and efficient tool products can significantly reduce the total production of enterprises. cost.
It is worth noting that while the tool product is constantly updating, the tool supplier has changed the tool material continuously, but the original tool body has not changed, and the changed tool price has not been adjusted. For the whole vehicle and parts manufacturing enterprises, when the processing efficiency of a certain process is lacking or dissatisfied, try to select a new tool product or change the original structure of the body product, which may increase the cost without increasing the cost. It has an unexpected boost to efficient processing. At the same time, with the responsible tool management personnel, I believe that while effectively ensuring the processing efficiency, it can greatly increase the production capacity.
