The technological improvements in boring tools mainly lie in the following four aspects.
Since the advent of Numerical Control (NC) technology, digital display technology has been widely applied in CNC machine tools and coordinate measuring machines. Furthermore, digital measuring tools such as digital micrometers and digital calipers are also widely used. However, the application of digital display technology in precision boring tools has progressed slowly, primarily due to the coolant used in boring operations and the high-speed rotation of the boring head.
In the past, boring operations on machining centers required extreme care to avoid coolant splashing into the electronic components of the boring head's digital display unit. Today, new boring tools with internal cooling designs have largely solved this problem. Because the coolant can directly reach the cutting area through channels inside the tool, complete isolation between the coolant and the boring head's digital display unit is achieved. In addition, the new CNC boring tools have a well-sealed exterior, effectively preventing contact between the coolant and the electronic components in the digital display unit.
In high-speed boring, the high-speed rotation of the boring head, centrifugal force, and inherent imbalance can all cause significant vibrations, damaging the sensitive digital display device. New boring heads, employing a built-in balancing mechanism, can reduce or eliminate harmful vibrations during high-speed boring. Precision boring heads with digital displays are now capable of high-speed boring at speeds up to 16,000 rpm.
The digital display of the new boring head directly shows the displacement of the boring bar slide, eliminating the need to determine the displacement through the rotation of the adjusting screw. Because the boring bar is directly mounted on the boring bar slide, the digital display reading accurately reflects the boring bar displacement, unaffected by screw travel errors. This feature of the digital display boring head allows for faster and more precise adjustment of the boring diameter and enables error compensation for machining deviations or tool wear.
Most boring tools require a cut-and-measure operation to determine their set dimensions. This involves first boring a small portion of the hole to be machined, then measuring the diameter of the hole. Typically, this means removing the boring tool from the machine tool and mounting it on a tool setter for fine-tuning to obtain the correct hole diameter. This pre-adjustment is necessary because directly reading and pre-adjusting the vernier scale of a standard boring head on the machine tool is quite difficult; however, this method can lead to out-of-tolerance hole dimensions or damage to the workpiece.
Because it is difficult to predict the tool tip deviation when mounting the boring tool on the machine tool, a cut-and-measure operation is needed for tool pre-adjustment. With newer, easily readable digital boring tools, it may be possible to fine-tune the boring diameter directly on the machine spindle. Even if the boring tool must be removed from the machine tool for hole diameter adjustment due to the feed limitation of the machine tool spindle, the tool adjustment process of the new digital display boring tool is faster and more accurate.
