Types and uses of tool holders in machining centers
The hilt is the connectome of the machine tool and the tool. The hilt is a key part of affecting the concentricity and dynamic balance, and it must not be treated as a normal part. The degree of concentricity can determine whether the cutting part of the cutter is evenly distributed during the rotation of the cutter. The dynamic imbalance in the rotation of the spindle produces periodic vibrations.
According to the main axes, the conical holes are divided into two categories
The taper of the main shaft of the machining center is usually divided into two categories:
The taper is 7:24 SK universal shank
The taper is 1:10 HSK vacuum handle
▌ taper for the 7:24 SK general handle
7:24 refers to the taper of the handle of the handle at 7:24, and the taper shank is longer. The cone surface also plays two important roles, namely the precise positioning of the handle relative to the spindle and the grip of the blade.
advantages: no self-locking, can achieve rapid loading and unloading of the cutting tool; The handle costs are relatively low as long as the taper Angle is processed to high precision to ensure the precision of the connection.
Weakness: when rotating at high speed spindle front cone hole expansion happens, the size of the expansion amount increases with the increase of rotation radius and speed, taper connecting stiffness decreases, the pull rod under the action of tension, the handle of the axial displacement will also change. The radial dimension of the shank changes after each change of blade, and there are problems with unstable positioning accuracy.
There are usually five standards and specifications for a generic handle with a taper of 7:24:
1. International standard IS0 7388/1 (IV or IT)
2. Japanese standard MAS BT (BT)
3. German standard DIN 2080 (NT or ST)
4. American standard ANSI/ASME (CAT)
5. DIN 69871 (JT, DIN, DAT or DV)
The nt-shaped handle is used to tighten the handle on the traditional machine tool. The other four handles are the handle of the handle at the center of the processing center.
1) at present, the most domestic use is DIN 69871 (namely JT) and Japanese MAS BT type;
2) the handle of DIN 69871 can also be installed on the machine tool of ANSI/ASME spindle tapered hole;
3) international standard IS0 7388/1 blade can also be installed on the machine tool of DIN 69871, ANSI/ASME spindle tapered hole, so the handle of IS0 7388/1 is the best in terms of versatility.
▌ taper is 1:10 HSK vacuum handle
HSK vacuum grip on the handle of the elastic deformation, not only handle the "cone of contact with the machine tool spindle hole 1:10 cone, and makes the handle of the flange disk and spindle surface also close contact, this kind of double contact system on high speed machining, connection rigidity and overlap accuracy is superior to" general handle.
HSK vacuum handle can improve the rigidity and stability of the system and the products in high speed machining precision, and shorten the time of the cutting tool replacement, play a very important role in high speed machining, the adaptation of machine tool spindle speed of 60000 r/min. HSK tool system is widely used in aerospace, automobile, precision mould and other manufacturing industries.
HSK handles include type A, type B, C, D, E, F and other specifications, which are often used in machining centers (automatic knife changing) with type A, E and F.
The biggest difference between type A and type E:
1. Type A has transmission slot and type E is not. So relatively speaking, the type A transmission torque is relatively large, which can be used for some heavy cutting. The E - type transmission torque is relatively small, can only carry out some light cutting.
2. There are manual fixed holes and direction slots in addition to the transmission slot on the handle of type A, so the balance is relatively poor. The E type is not, so the E type is more suitable for high-speed machining. The e-type and f-type institutions are exactly the same, and the difference is that the same type of type E and F handles (such as E63 and F63), and the taper of the f-shaped handle are smaller. In other words, the flange diameter of E63 and F63 is phi 63, but the cone size of F63 is only the same size as that of E50. So compared with E63, the speed of F63 is faster (the spindle bearing is small).
The form of knife handle
▌ collet chuck the handle
It is mainly used for the clamping of drill, milling cutter, tap and other straight shank tools and tools. The elastic deformation of the card spring is 1mm, and the range of clamping is 0.5-32mm in diameter.
▌ hydraulic chuck
A - locking screw, tighten the locking screw with the inner hexagon wrench;
B - lock the piston and press the hydraulic medium into the expansion chamber;
C - expansion chamber, under pressure from liquid extrusion;
D-thin expansion bushing, in the locking process, the tool holder center positioning and uniform envelope.
E - special seals ensure ideal sealing and long service life.
▌ heating the handle
Apply the induction heating technology to heat the tool holder on the handle to expand the diameter of the tool, and then put the cold knife rod into the hot shank. The heating tool handle clamping force is big, dynamic balance is good, suitable for high-speed machining. The repeated positioning accuracy is high, usually within 2 mu m, and the radial pulse is within 5 mu m. Good anti-fouling ability, good anti-interference ability in processing. However, each specification can only be fitted with a tool with a handle diameter, and a set of heating equipment is required.
The principle of heat shrinkable shank loading:
Comprehensive evaluation of hilt and hilt:
▌ other type of handle