With the popularity of CNC machine tools, thread milling technology in the machinery manufacturing industry more and more applications. Thread milling is through the three-axis CNC machine tool linkage, the use of screwdriver for screw interpolation milling and the formation of threads, the tool in the horizontal plane for each week to do a circular motion in the vertical plane is a straight line to move a pitch. Thread milling has many advantages such as high processing efficiency, high thread quality, good tool and good processing safety. There are many kinds of thread milling tools which are used at present. This paper analyzes seven common thread milling cutters from the application characteristics, tool structure and processing technology.
General machine clip type Road Milling Tools
Machine-mounted Road Milling Tools is the most commonly used and inexpensive tool in thread milling. Its structure is similar to that of ordinary machine clamp. It is made up of reusable arbor and easily replaceable blade. If you need to process the taper thread, but also can be used to process the taper thread of the special knife and the blade, the blade with a number of thread cutting teeth, the tool can be processed a week along the helical processing of a number of threaded teeth, There are 5 2mm thread cutting teeth of the cutter, along the helix processing a week can be processed out of 5 thread depth 10mm thread teeth. In order to further improve the processing efficiency, the choice of multi-blade machine-type Road Milling Tools. By increasing the number of cutting edges, the feed rate can be significantly increased, but the radial and axial positioning errors between each blade distributed on the circumference will affect the threading accuracy. Such as multi-blade machine Road Milling Tools milling thread processing accuracy is not satisfied, but also try to install only one blade for processing. In the selection of machine-clamped Road Milling Tools, should be processed according to the diameter of the thread, depth and workpiece materials and other factors, try to use a larger diameter of the knife and the appropriate blade material. The threading depth of the thread clamp Road Milling Tools is determined by the effective cutting depth of the arbor. Since the blade length is less than the effective cutting depth of the arbor, the machining is required when the length of the machined thread is greater than the length of the blade.
Common integral Road Milling Tools
The Road Milling Tools is mostly made of solid carbide material, and some also use the coating. Integral Road Milling Tools is compact, more suitable for processing, small diameter thread; also for the processing of taper thread thread Road Milling Tools. This kind of tool rigidity is better, especially with the spiral groove of the Road Milling Tools, in the processing of high hardness materials can effectively reduce the cutting load, improve processing efficiency. The cutting edge of the integral Road Milling Tools is covered with thread-machined teeth and can be processed along the helix for one week to complete the entire threading process without the need for a layer-like tool, so the processing efficiency is high but the price is relatively expensive The
Full Road Milling Tools with chamfering function
The Road Milling Tools with chamfer function is similar to the conventional integral Road Milling Tools, but has a special chamfer at the root of the cutting edge, which can be machined at the same time. There are three ways to process chamfering. When the tool diameter is large enough, you can use the chamfer edge to drill down the chamfer, which is limited to the machining of the internal thread hole chamfering. When the tool diameter is small, you can use the chamfering edge to create a chamfer by circular motion. However, in the use of cutting edge root chamfering edge chamfering, pay attention to the cutting part of the thread and the thread should have a certain gap between, in order to avoid interference. If the machined thread depth is less than the effective cutting length of the tool, the tool will not be able to achieve the chamfering function, so the tool should be selected to ensure that the effective cutting length and thread depth match each other.
Road Milling Tools
Threaded milling cutter made of the overall carbide, is a small diameter internal thread efficient processing tool. Threaded drill can be completed at one time drill thread bottom hole, hole chamfer and internal thread processing, reducing the number of tool use. But the disadvantage of this tool is the versatility is poor, the price is more expensive. The tool consists of the drilling part of the head, the middle of the thread milling part and the root of the cutting edge of the three parts of the chamfer. Drilling part of the diameter is the tool can be processed thread diameter. By drilling part of the diameter of the restrictions, a Road Milling Tools can only be processed a kind of internal thread. In the selection of thread drilling cutter, not only to consider the size of the screw hole is processed, but also pay attention to the effective length of the tool with the depth of the hole to be matched, or can not achieve chamfering function.
Threaded helical drill
Threaded screwdriver is also an integral carbide tool for efficient machining of internal threads, and can also be used to process bottom holes and threads at one time. The end of the tool has a cutting edge like an end mill. As the screw screw angle is not large, so the tool to do the spiral movement of the thread, the end of the cutting edge of the first part of the workpiece material processing hole, and then processed by the rear of the tool thread. Some threaded auger cutter also has a chamfer, which can be machined at the same time. The tool processing efficiency is very high, and versatility than the thread drilling cutter, the tool can be processed within the thread diameter range d ~ 2d (d for the diameter of the body).
Milling Road Milling Tools
Milling the deep Road Milling Tools is a single tooth Road Milling Tools. The general Road Milling Tools has a plurality of threading teeth on the cutting edge, the contact area between the tool and the workpiece is large, the cutting force is also large, and the diameter of the tool must be smaller than the thread diameter when machining the internal thread. As the diameter of the cutter body is limited, the tool is rigorous, and the milling tool is unilateral force. When the deep thread is milled, it is easy to make the knife phenomenon and affect the machining precision. Therefore, the effective cutting depth of the Road Milling Tools is about Knife body diameter of 2 times. The use of single-tooth milling deep Road Milling Tools can better overcome the above shortcomings. As a result of reducing the cutting force, can greatly enhance the thread processing depth, the effective cutting depth of the knife up to the diameter of the blade 3 to 4 times.