Is the tool holder of a machine tool a tool?
July 18, 2019
Tool shank is the connection of machine tool and tool. Tool shank is a key link affecting concentricity and dynamic balance. It must not be treated as a general component. Concentricity can determine whether the cutting amount of each cutting edge is uniform under the circumstance of rotating one cycle, and the dynamic unbalance will produce periodic vibration when the spindle rotates.
I. There are two main types of spindle conical holes.
According to the taper of the tool hole on the spindle of the machining center, there are usually two main types:the taper of the tool hole on the spindle of the machining center and the taper of the tool hole on the spindle.
SK universal tool holder with taper of 7:24
HSK vacuum tool holder with taper of 1:10
SK universal tool holder with taper 7:24
7:24 refers to the taper of the tool handle is 7:24, which is located on a single taper surface and has a longer taper handle. Cone surface plays two important roles at the same time, that is, precise positioning of the tool handle relative to the spindle and clamping of the tool handle.
Advantages: Without self-locking, the tool can be quickly loaded and unloaded; manufacturing tool shank can ensure the accuracy of the connection as long as the taper angle is processed to high accuracy, so the cost of tool shank is relatively low.
Disadvantage: When spindle is rotated at high speed, the cone hole at the front end of spindle will expand, the expansion will increase with the increase of rotation radius and speed, the rigidity of taper connection will decrease, and the axial displacement of tool holder will change under the pull force of tie rod. The radial dimension of the tool holder will change every time the tool is changed, and the problem of unstable repetitive positioning accuracy exists.
The universal tool holder with taper of 7:24 usually has five standards and specifications:
1. International Standard IS0 7388/1 (IV or IT for short)
2. Japanese Standard MAS BT (abbreviated as BT)
3. German Standard DIN 2080 (NT or ST for short)
4. American Standard ANSI/ASME (abbreviated as CAT)
5. DIN 69871 (JT, DIN, DAT or DV for short)
Tension mode:
NT type tool holder is a kind of tool holder which is tightened by pull rod on traditional machine tool, also known as ST in China. The other four kinds of tool holders are tightened by pull nail at the end of tool holder on machining center.
Generality:
1) At present, DIN 69871 (JT) and Japanese MAS BT tool holders are the most widely used tool holders in China.
2) The tool handle of DIN 69871 can also be installed on the machine tool of ANSI/ASME spindle taper hole.
3) IS0 7388/1 tool holder can also be installed on DIN 69871 and ANSI/ASME spindle taper hole machine tools, so IS0 7388/1 tool holder is the best in terms of versatility.
HSK Vacuum Toolholder with_taper of 1:10
The elastic deformation of HSK vacuum tool holder depends on the tool holder, which not only contacts the 1:10 taper surface of the tool holder with the 1:10 taper surface of the spindle hole of the machine tool, but also makes the flange surface of the tool holder closely contact with the spindle surface. This double-sided contact system is superior to the general tool holder of 7:24 in high speed machining, connection rigidity and coincidence accuracy.
HSK vacuum tool holder can improve the rigidity and stability of the system as well as the product accuracy in high-speed machining, and shorten the time of tool replacement. It plays an important role in high-speed machining. It can adapt to the spindle speed of machine tools up to 60,000 rpm. HSK tool system is widely used in aerospace, automobile, precision die and other manufacturing industries.
HSK tool holder has a variety of specifications, such as A, B, C, D, E and F. Among them, A, E and F are commonly used in machining centers (automatic tool change).
The biggest difference between Type A and Type E is:
1. Type A has drive grooves, but type E does not. Therefore, relatively speaking, the A-type transfer torque is larger, and some heavy cutting can be carried out relatively. The E-type transmission of the torque is relatively small, can only carry out some light cutting.
2. In addition to the transmission groove, there are also manual fixed holes and direction grooves on the A-type tool handle, so the balance is relatively poor. The E-type is not, so the E-type is more suitable for high-speed machining. The mechanism of E-type and F-type is exactly the same. The difference between them is that the cone of E-type and F-type tool holders (e.g. E63 and F63) is smaller than that of F-type tool holders. That is to say, the flange diameters of E63 and F63 are both 63, but the cone size of F63 is only the same as that of E50. Therefore, compared with E63, the speed of F63 is faster (spindle bearings are smaller).
2. Tool-mounting Form of Tool Handle
_spring chuck handle
It is mainly used for clamping straight shank cutters and tools such as drills, milling cutters and taps. The elastic deformation of clamping spring is 1 mm and the clamping range is 0.5-32 mm in diameter.
_hydraulic chuck
A - Lock the screw, tighten the lock screw with the inner hexagonal wrench;
B - Lock the piston and press the hydraulic medium into the expansion chamber.
C-expansion chamber, pressure produced by liquid extrusion;
The D-thin expansion bushing can locate the center of tool clamping rod and envelop it evenly during the locking process.
E-special seals ensure ideal seals and long service life.
_Heating Tool Handle
Applying induction heating technology to heat the clamping part of the tool holder, the diameter of the tool holder will expand, and then the cold tool holder will be put into the hot tool holder. The heating tool holder has large clamping force and good dynamic balance, which is suitable for high-speed machining. Repeated positioning accuracy is high, generally within 2 micron, radial jump within 5 micron; anti-fouling ability is good, anti-interference ability is good in processing. However, each specification of tool shank is suitable for installing only one kind of tool with handle diameter, which requires a set of heating equipment.
