Functions and characteristics of the seven most po

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Functions and characteristics of seven commonly used thread milling tools

with the popularity of numerical control machine tools, thread milling technology is more and more applied in the machinery manufacturing industry. Thread milling is through the three-axis linkage of CNC machine tools, using 3 Instead of regular thread milling cutter for spiral interpolation milling to form threads, the cutter moves in a straight line with a pitch every week on the horizontal plane. Thread milling has many advantages, such as high machining efficiency, high thread quality, good tool versatility, good machining safety and so on

there are many kinds of thread milling tools used at present. This paper analyzes seven common thread milling tools from the application characteristics, tool structure, processing technology and so on

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I. ordinary machine clamp thread milling cutter

machine clamp thread milling cutter is the technology and industrialization of new materials at the cutting edge of threads. It breaks through the most commonly used and low-cost cutter in milling. Its structure is similar to that of ordinary machine clamp milling cutter, which is composed of reusable cutter rods and easily replaceable blades. If you need to process conical threads, you can also use the special tool bar and blade for processing conical threads. This kind of blade is equipped with multiple thread cutting teeth, and the tool can process multiple thread teeth at one time after processing along the spiral line. For example, if you use a milling cutter with 5 2mm thread cutting teeth and process along the spiral line for one week, you can process 5 thread teeth with a thread depth of 10mm

in order to further improve the processing efficiency, multi blade machine clamp thread milling cutter can be selected. By increasing the number of cutting edges, the feed rate can be significantly improved, but the radial and axial positioning errors between each blade distributed on the circumference will affect the thread machining accuracy. If the thread accuracy of multi blade machine clamp thread milling cutter is not satisfied, you can also try to install only one blade for processing. When selecting clamp type thread milling cutter, the cutter bar with larger diameter and appropriate blade material should be selected as far as possible according to the diameter, depth and workpiece material of the processed thread. The thread processing depth of the clamp thread milling cutter is determined by the effective cutting depth of the cutter bar. Because the length of the blade is less than the effective cutting depth of the tool bar, when the depth of the processed thread is greater than the length of the blade, it needs to be processed in layers

second, ordinary integral thread milling cutter

integral thread milling cutters are mostly made of integral cemented carbide materials, and some are also coated. The integral thread milling cutter has a compact structure, which is more suitable for processing medium and small diameter threads; There are also integral thread milling cutters for machining taper threads. This kind of cutter has good rigidity, especially the integral thread milling cutter with spiral groove, which can effectively reduce the cutting load and improve the processing efficiency when processing high hardness materials. The cutting edge of the integral thread milling cutter is full of thread processing teeth, and the whole thread processing can be completed by processing along the spiral line for one week. There is no need for layered processing like the clamp type cutter, so the processing efficiency is higher, but the price is also relatively expensive

III. integral thread milling cutter with chamfer function

the structure of integral thread milling cutter with chamfer function is similar to that of ordinary integral thread milling cutter, but the design of the root circuit of the cutting edge greatly reduces the special chamfer edge, which can process the chamfer at the end of the thread while processing the thread. There are three ways to process the chamfer. When the tool diameter is large enough, the chamfer can be directly countersunk with the chamfer edge. This method is only limited to processing the chamfer of the internal thread orifice. When the tool diameter is small, the chamfer edge can be used to process the chamfer through circular motion. However, when using the chamfering edge at the root of the cutting edge for chamfering, pay attention to a certain gap between the thread cutting part of the tool and the thread to avoid interference. If the processed thread depth is less than the effective cutting length of the tool, the tool will not be able to achieve the chamfer function. Therefore, when selecting the tool, ensure that its effective cutting length matches the thread depth

IV. thread drill and milling cutter

the thread drill and milling cutter is made of integral cemented carbide, which is an efficient tool for machining small and medium-sized internal threads. The thread drill and milling cutter can complete the drilling of thread bottom hole, hole chamfering and internal thread processing at one time, reducing the number of tools used. But the disadvantage of this kind of cutting tool is poor versatility and relatively expensive price. The tool consists of three parts: the drilling part of the head, the thread milling part in the middle and the chamfer edge at the root of the cutting edge. The diameter of the drilling part is the bottom diameter of the thread that the tool can process. Limited by the diameter of the drilling part, a thread drill and milling cutter can only process internal threads of one specification. When selecting the thread drill and milling cutter, we should not only consider the specification of the processed thread hole, but also pay attention to the matching between the effective machining length of the cutter and the depth of the processed hole, otherwise the chamfer function cannot be realized

v. screw drill milling cutter

screw drill milling cutter is also an integral cemented carbide tool for efficient machining of internal threads, and it can also process bottom holes and threads at one time. The end of the tool has a cutting edge like an end mill. Because the spiral rise angle of the thread is not large, when the tool performs spiral motion to process the thread, the end cutting edge first cuts off the workpiece material to process the bottom hole, and then processes the thread from the rear of the tool. Some thread auger milling cutters also have chamfering edges, which can process the chamfer of the orifice at the same time. The machining efficiency of this tool is very high, and its versatility is better than that of thread drill and milling cutter. The range of internal thread aperture that the tool can machine is d-2d (D is the tool body diameter)

VI. deep thread milling cutter

deep thread milling cutter is a single tooth thread milling cutter. Generally, there are multiple thread processing teeth on the blade of thread milling cutter, the contact area between the cutter and the workpiece is large, and the cutting force is also large, and the diameter of the cutter must be smaller than the thread aperture when machining internal threads. Because the cutter body diameter is limited, which affects the rigidity of the cutter, and the cutter is forced on one side when milling threads, it is easy to yield the cutter when milling deeper threads, which affects the machining accuracy of threads. Therefore, the effective cutting depth of general thread milling cutters is about 2 times of their cutter body diameter. The use of single tooth deep thread milling tools can better overcome the above shortcomings. Because the cutting force is reduced, the thread processing depth can be greatly improved, and the effective cutting depth of the tool can reach 3-4 times of the tool body diameter

VII. Thread milling tool system

versatility and efficiency is a prominent contradiction of thread milling tools. Some tools with composite functions have high machining efficiency but poor versatility, while the efficiency of tools with good versatility is often not high. To solve this problem, many tool manufacturers have developed modular thread milling tool systems. The tool is generally composed of tool shank, countersink chamfer edge and general thread milling cutter. Different types of countersink chamfer edge and thread milling cutter can be selected according to processing requirements. This tool system has good versatility and high machining efficiency, but the tool cost is high

the above outlines the functions and characteristics of several commonly used thread milling tools. When milling threads, cooling is also very important. It is recommended to use machine tools and tools with internal cooling function. As the tool rotates at high speed, the external coolant is not easy to enter under the action of centrifugal force. In addition to the internal cooling method, which can cool the tool well, it is more important that the high-pressure coolant is conducive to chip removal when machining blind hole threads. In particular, a higher internal cooling pressure is required when machining small-diameter internal thread holes to ensure smooth chip removal. In addition, when selecting thread milling tools, we should also comprehensively consider the specific processing requirements, such as production batch, number of screw holes, workpiece material, thread accuracy, size specification and many other factors, and comprehensively select tools

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