Our company supports ultra-small diameter deep hole drilling (deep hole drilling) from Φ0.5, which cannot be achieved by conventional gun drilling. This enables deep hole drilling (deep hole drilling) with high surface roughness, which is a characteristic of gundrilling, even for holes as small as Φ0.5.
With the Monodzukuri subsidy in 2013, we reviewed all parts of the gundrilling machine based on the idea of specializing in small diameters, and completed a new type of gundrilling machine for extremely small diameters that incorporates a number of new mechanisms. As a result, we are now able to handle deep hole drilling (deep hole drilling) with an extremely small diameter of 0.5mm, which was not possible with conventional machines.
From belt drive system to new spindle rotation motor
We have achieved the deep hole drilling of 400 mm in depth with a diameter of 1 mm, that is, L/D = 400 with an extremely small diameter of 1 mm, by combining our special gun drilling machine for small diameter and deep hole drilling technology. At present, we are still developing the technology to extend the L/D even further, and we are constantly researching deep hole drilling technology that goes into unexplored areas.
Main spindle rotation...
It is considered to be the most important position in the cutting process. For this reason, we have been working on the development of the spindle rotation motor since the beginning of our involvement in gun drills. Conventional gun drills manufactured by our company used a belt drive system.
What is belt drive system? Let me explain it briefly here. The belt drive system is a drive system that uses a belt and pulley to transmit the motor power to the spindle to rotate the spindle.
For gundrilling machines that require cutting fluid to be supplied to the tool, it has been common practice to locate the motor in a separate location. However, because of the following disadvantages, we have developed a new method of spindle rotation motor.
Because of the belt and pulley drive, rotational vibration is transmitted to the spindle itself.
Power transmission efficiency is poor.
Space is required in the height direction.
Large number of parts (transmission parts, etc.)
The motor we developed to solve this problem is the built-in motor, which is directly attached to the hollow shaft.
By using this type of
Eliminating transmission parts reduces vibration and improves rotational accuracy.
Reduced number of parts → Space saving
However, there are still improvements left to be made.
Due to the characteristics of the inverter (frequency command) control, there is no feedback (return of rotation information) of the rotation speed information, so uneven rotation occurs when the load changes. (It is not possible to respond to the load fluctuation during processing.
Rotation accuracy in the low speed range is reduced.
The machining range is limited due to the lack of torque in the low speed range.
At the end of 2010, we started to develop a new spindle unit. We asked ourselves, "Can't we use a servo motor that can provide feedback control and torque from the low speed range for the spindle? This idea led to the birth of the new servo motor.
The hollow resolver enables loop control of the rotation speed to maintain a constant rotation speed even when the load fluctuates.
Stable rotational accuracy.
Maximum torque can be produced from low rpm.
The actual hole diameter that can be machined is about twice as large as that of our company.
Deep hole drilling of difficult-to-cut materials, which was not possible with conventional machines, is now possible.
Hollow resolver: A sensor used to detect the rotational position of a motor.
Loop control: Control in which the output is fed back to the input. In this case, the rotation shall be controlled based on the rotation speed information.
A servomechanism is a mechanism that automatically operates to follow the target value of the position, orientation, and posture of an object as a control quantity. An automatic control device. The word "servo" comes from the Latin word "servus" (meaning "slave" or "servant" in English).
We are doing research and development with special specification gun drills in cooperation with BOTEK.