Extra long reach end mills are often used in the daily processing of molds. They are rotary cutters with one or more teeth for milling. When working, each cutter tooth intermittently cuts off the margin of the workpiece. Extra long reach end mills are mainly used for machining planes, steps, grooves, forming surfaces and cutting off workpieces on milling machines. There are many types of milling cutters with different structures. There are various types of cylindrical milling cutters, face milling cutters, end milling cutters, disc milling cutters, saw blade milling cutters, forming milling cutters, etc. on the market, with a wide range of applications.
According to the Extra long reach end mills structure and installation method, it can be divided into shank milling cutter and hole milling cutter.
1. Shank milling cutters are divided into straight shank and taper shank. Generally, smaller milling cutters with a diameter less than 20mm are made into straight shanks. Milling cutters with larger diameters are mostly made of taper shanks. This kind of milling cutter is mostly used for end milling.
①Because the teeth of the end mill are distributed on the end surface and cylindrical surface of the milling cutter, it is mostly used for processing planes on vertical lifting table milling machines, and can also be used for processing planes on horizontal lifting table milling machines.
②Keyway milling cutters and T-slot milling cutters are specially designed for processing keyway and T-slots.
③Dovetail milling cutter is specially used for milling dovetail grooves.
2. The hole milling cutter is suitable for horizontal milling machine processing, can process various surfaces, and has a wide range of applications.
2. There are a variety of commonly used types of milling cutters according to their purposes.
1. Cylindrical milling cutter: used for processing planes on horizontal milling machines. The cutter teeth are distributed on the circumference of the milling cutter. According to the tooth shape, they are divided into straight teeth and spiral teeth. According to the number of teeth, there are two types: coarse teeth and fine teeth. The helical coarse-tooth milling cutter has few teeth, high tooth strength and large chip space, suitable for rough machining, and fine-tooth milling cutters are suitable for finishing.
2. Face milling cutter: used for vertical milling machine, face milling machine or gantry milling machine to process flat end faces and circumferences. There are cutter teeth, coarse teeth and fine teeth. Its structure has three types: integral type, insert type and indexable type.
3. The end mill is used for processing grooves and step surfaces, etc. The cutter teeth are on the circumference and end surface, and cannot be fed along the axial direction when working. When the end mill has end teeth passing through the center, it can feed axially. 4. Three-sided edge milling cutter: used to process various grooves and stepped surfaces, with teeth on both sides and circumference.
5. Angle milling cutter: used for milling grooves at a certain angle, there are two kinds of single-angle and double-angle milling cutters.
6. Saw blade milling cutter: used to process deep grooves and cut off the workpiece, with more teeth on the circumference. In order to reduce friction during milling, there is a 15'-1° secondary deflection angle on both sides of the cutter teeth. In addition, there are keyway milling cutters, dovetail milling cutters, T-slot milling cutters and various forming milling cutters.
Three, the structure of the milling cutter
Divided into 4 types.
1. Integral type: The cutter body and the cutter teeth are made into one body.
2. Integral welding tooth type: The cutter teeth are made of cemented carbide or other wear-resistant tool materials and brazed on the cutter body.
3. Insert tooth type: The tooth is fastened to the body of the tool by mechanical clamping. This replaceable cutter tooth can be a cutter head of integral cutter material or a cutter head of welding cutter material. The milling cutter with the cutter head mounted on the cutter body is called the internal sharpening type, and the cutter head is individually sharpened on the fixture as the external sharpening type.
4. Indexable type: This structure has been widely used in face milling cutters, end mills and face milling cutters.
Fourth, the installation of the milling cutter
(1) Installation of shank milling cutter
1. Straight shank milling cutter installation: Straight shank milling cutters are usually installed with spring chucks. When installing, tighten the nut to make the spring sleeve shrink radially to clamp the shank of the milling cutter.
2. Installation of taper shank milling cutter: When the size of the taper shank of the milling cutter is the same as the taper hole at the end of the spindle, it can be directly inserted into the taper hole and tightened with a tie rod. Otherwise, use transitional taper sleeves for installation
(2) Installation of milling cutter with hole
Hole milling cutters should be installed with a milling cutter bar. First, insert one end of the milling cutter bar cone into the spindle taper hole and tighten it with a tie rod. The appropriate position of the milling cutter is adjusted through the sleeve, and the other end of the cutter bar is supported by a hanger.
Five, the choice of milling cutter body
1. First, when choosing a milling cutter, consider the number of teeth. For example, a coarse-tooth milling cutter with a diameter of 100mm has only 6 teeth, while a close-tooth milling cutter with a diameter of 100mm can have 8 teeth. The size of the tooth pitch will determine the number of cutter teeth involved in cutting at the same time during milling, and affect the smoothness of cutting and the requirements for machine tool cut rate. Each milling cutter manufacturer has its own series of coarse-tooth and dense-tooth face milling cutters.
2. The rough tooth milling cutter is mostly used for rough machining because it has a larger chip pocket. If the chip pocket is not large enough, it will cause difficulty in chip rolling or increase the friction between the chips and the cutter body and workpiece. At the same feed rate, the cutting load per tooth of a coarse-tooth milling cutter is larger than that of a close-tooth milling cutter.
3. When finishing milling, the cutting depth is shallow, generally 0.25～0.64mm, the cutting load per tooth is small (about 0.05～0.15mm), the required power is not large, you can choose a close-tooth milling cutter, and you can choose a larger one Feed rate. Since the metal removal rate in fine milling is always limited, it does not matter if the chip pockets of the close-tooth milling cutter are smaller.
4. For spindles with larger tapered hole specifications and better rigidity, a close-tooth milling cutter can also be used for rough milling. Since a close-tooth milling cutter has more teeth involved in cutting at the same time, when using a larger cutting depth (1.27～5mm), pay attention to whether the power and rigidity of the machine tool are sufficient, and whether the chip pocket of the milling cutter is large enough. The chip removal situation needs to be tested and verified. If there is a problem with chip removal, the cutting amount should be adjusted in time.
5. When carrying out heavy-load rough milling, excessive cutting force can cause vibration of the machine with poor rigidity. This chattering can cause the chipping of the carbide inserts, thereby shortening tool life. The choice of coarse-tooth milling cutter can reduce the power requirements of the machine tool. Therefore, when the spindle hole size is small (such as R-8, 30#, 40# taper hole), the rough tooth milling cutter can be effectively used for milling.
