Back boring tool is a tool used for back boring. Back boring refers to the processing method of boring the back of the hole after the tool passes through the existing through hole on the CNC machine tool.
During back boring, since the tool needs to pass through the through hole before cutting, the back boring tool usually has a special structural design. Common back boring tools are of the following types:

1. Back boring with eccentric boring tool: This boring tool has a simpler design, but there may be certain limitations during processing. For example, for the processing of small holes, deep holes or hard materials, there may be problems such as insufficient rigidity and easy vibration.

2. Back boring with rotating blade: Through the forward and reverse rotation of the machine tool spindle, the inertia principle of the object is used to control the expansion and retraction of the blade. When the spindle is reversed, the blade is in a closed state and can pass through the through hole to reach the specified position; when the spindle is forward, the blade is thrown out and expanded by inertia to enter the cutting state.

3. Use special tools for back boring: For example, two centrifugal weights are installed in the closed cavity of a special tool. When not in operation or at rest, the centrifugal weights are in the middle position under the action of the reset spring. When the rotation speed of the tool bar reaches the critical speed, the centrifugal weights will move outward, drive the intermediate gear to rotate through the rack, and then drive the blade control rod to rotate at a small angle, so that the blade extends or retracts.

When designing and using back boring rough boring tools, some issues need to be paid attention to to ensure the stability and quality of processing.

1. Rigidity of the tool system. Including the rigidity of the tool handle, blade, boring bar and the middle connecting part. Because back boring processing belongs to cantilever processing, and sometimes the tool bar is elliptical or eccentric, the rigidity of the tool system is particularly important when processing small holes, deep holes and hard workpieces;

2. Dynamic balance of the tool system. If the tool itself has unbalanced mass relative to the rotation axis of the tool system, especially when the tool bar is elliptical and eccentric, the centrifugal force generated by the imbalance during rotation will be more significant, which may cause vibration;

3. Cutting conditions. Such as the shape of the blade, cutting speed, feed rate, feed rate, and the supply method and type of emulsion, etc., can only achieve reasonable cutting conditions by improving according to the actual situation on site;

4. Tool clamping. When boring holes, the center height of the tool is an important factor leading to tool failure. It is recommended that the tool should be installed slightly higher than the center height (but as close to the center height as possible), so that the normal back angle of the tool relative to the workpiece can be increased, the cutting conditions can be improved, and the possibility of tool failure can be reduced;

5. The use of chip removal and coolant. When boring small holes, it is necessary to ensure the effective discharge of chips. Some tool manufacturers will develop blades with cooling grooves along the cutting edge to allow the cutting fluid to flow directly to the cutting edge to prevent chip blockage and tool damage.

Different types of back boring and rough boring tools have their own characteristics and applicable scope. In practical applications, it is necessary to select suitable tools based on specific processing requirements, workpiece materials, machine tool performance and other factors, and reasonably set processing parameters to achieve ideal processing results.