Today I want to talk to you about the knowledge of the tool handle of the machining center. Today, CNC machine tools are widely used in factories, and these machines and tools used come from all over the world, with different models and standards. Do you know what 7:24 means in the BT tool handle of the machining center? Do you know what BT, NT, JT, IT, CAT are?

The tool handle is the connection of the machine tool and the tool, the tool handle is a key link that affects the concentricity and dynamic balance, and it must not be regarded as a general component. The concentricity can determine whether the cutting amount of each cutting edge part is uniform when the tool is rotated once. When the spindle rotates, the dynamic imbalance will produce periodic vibration.

1. It is divided into two categories according to the spindle cone hole

According to the taper of the machining center spindle cutter hole is usually divided into two categories:

SK Universal shank with a taper of 7:24

HSK vacuum shank with a taper of 1:10

SK Universal shank with a taper of 7:24

7:24 refers to the tool shank taper of 7:24, which is positioned for a separate cone, and the cone shank is longer. The surface of the cone plays two important roles at the same time, that is, the precise positioning of the tool holder relative to the spindle and the realization of the tool holder clamping.

Ÿ Advantages: no self-locking, can achieve fast loading and unloading tools; As long as the taper Angle is processed to high precision, the accuracy of the connection can be ensured, so the cost of the handle is relatively low.

Disadvantages: When rotating at high speed, the taper hole at the front end of the spindle will expand, the size of the expansion will increase with the increase of the rotation radius and the speed, the taper connection stiffness will decrease, and the axial displacement of the tool holder will also change under the action of the pull rod tension. After each tool change, the radial size of the tool handle will change, and there is a problem of unstable positioning accuracy.

Universal tool handles with a taper of 7:24 are usually available in five standards and specifications:

1. International Standard IS0 7388/1 (IV or IT)

2. Japanese Standard MAS BT (BT)

3. German standard DIN 2080 (NT or ST for short)

4. American Standard ANSI/ASME (CAT)

5. DIN 69871 (JT, DIN, DAT or DV)

Tightening method:

NT tool handle is in the traditional machine tool through the pull rod to tighten the tool handle, also known as ST; The other four kinds of tool handles are pulled tight on the machining center through the pull nail at the end of the tool handle.

Versatility:

1) At present, the most used tool handles in China are DIN 69871 (that is, JT) and MAS BT in Japan;

2) The tool handle of DIN 69871 can also be mounted on machine tools with ANSI/ASME spindle taper holes;

3) IS0 7388/1 tool holder can also be installed on DIN 69871, ANSI/ASME spindle cone hole machine tools, so in terms of versatility, IS0 7388/1 tool holder is the best.

HSK vacuum shank with a taper of 1:10

HSK vacuum tool holder relies on the elastic deformation of the tool holder, not only the 1:10 cone of the tool holder is in contact with the 1:10 cone of the main shaft hole of the machine tool, but also the flange disk of the tool holder is in close contact with the spindle face. This double-sided contact system is superior to the universal tool holder in high-speed processing, connection rigidity and coincidence accuracy.

HSK vacuum tool handle can improve the rigidity and stability of the system and the accuracy of the product in high-speed machining, and shorten the time of tool replacement, which plays a very important role in high-speed machining, and it can adapt to the spindle speed of the machine tool to 60,000 RPM. HSK tool systems are being widely used in aerospace, automotive, precision mold and other manufacturing industries.

HSK tool handles have A type, B type, C type, D type, E type, F type and other specifications, which are commonly used in machining centers (automatic tool change) on the A type, E type and F type.

The biggest difference between Type A and Type E:

1. Type A has a drive slot while type E does not. Therefore, relatively speaking, the A-type transmission torque is large, and some heavy cutting can be relatively carried out. The torque transmitted by the E-type is relatively small, and only some light cutting can be performed.

2. In addition to the transmission groove on the A-type tool handle, there are manual fixing holes, direction slots, etc., so the balance is relatively poor. The E type does not, so the E type is more suitable for high-speed machining. The mechanism of type E and type F is exactly the same, the difference between them is that the same name of type E and F shank (such as E63 and F63), the taper of the F shank is smaller. In other words, the flange diameter of E63 and F63 is φ63, but the cone size of F63 is only the same as that of E50. Therefore, compared with the E63, the F63 speed will be faster (the main shaft bearing is small).

2. Tool holder mounting form

Shank with spring chuck

Mainly used for drill, milling cutter, tap and other straight handle tools and tools clamping, the spring elastic deformation of 1mm, clamping range in diameter 0.5~32mm.

Hydraulic chuck

A- Locking screw, use a hex wrench to tighten the locking screw;

B- Lock the piston and press the hydraulic medium into the expansion chamber;

C- expansion chamber, pressure generated by liquid extrusion;

D-thin expansion bushing, positioning the tool holder center and evenly enveloping it during locking.

E-special seals ensure ideal sealing and long service life.

Heating tool handle

Apply induction heating technology to heat the tool clamping part on the tool handle, so that its diameter will expand, and then put the cold tool rod into the hot tool handle. Heating tool handle clamping force is large, dynamic balance is good, suitable for high-speed machining. High repeated positioning accuracy, generally within 2μm, radial runout within 5μm; Good anti-fouling ability, good anti-interference ability in processing. However, each specification tool handle is only suitable for installing a tool with a handle diameter, and a set of heating equipment is required.

Heat shrink tool holder clamping principle:

Tool handle comprehensive evaluation and comparison:

Other types of handle