Application of Frequency Converter in Modification of Single-arm Planer
Preface
The B1012 single-arm planer has been in use for over 30 years. Its worktable transmission system originally relied on a DC motor-generator set, which was prone to frequent failures and consumed a significant amount of energy. To address these issues, an inverter-controlled motor system was introduced. This modern solution offers advantages such as energy efficiency, easy speed adjustment, and simplified maintenance. As a result, a general-purpose inverter was selected for the retrofitting of this machine tool.
1 Overview of the B1012A Single-Arm Planer Before Retrofitting
The main components of the single-arm planer include the bed, table, column, beam, worktable transmission system, feed box, lubrication system, hydraulic safety device, and electrical equipment. The worktable's transmission system used a combination of a DC generator set and a second gear to achieve deceleration, reversal, and slow cutting, making it a key part of the main drive system. Meanwhile, the beam clamping, lifting, and the movement and rotation of the tool holder were part of the auxiliary drive system. The automatic cycle control for the worktable movement was implemented using a combined proximity switch.
2 Control Requirements for the Single-Arm Planer
a. Achieve smooth, stepless speed regulation with a wide range of speed control;
b. Allow independent adjustment of forward and backward speeds based on different workpieces;
c. Provide excellent starting and braking performance;
d. Ensure a simple, safe, and reliable system that is easy to maintain, low in noise, and highly efficient with significant energy savings.
3 Retrofitting the Worktable Main Drive System
3.1 Selection of Motor, Inverter, and External Components
The main drive system of the worktable now uses a Y225M-6, 37 kW asynchronous motor. A FRN45G11S-4CX inverter from Fuji Electric was chosen for the conversion. Considering the specific operating characteristics of the single-arm planer, the inverter was selected to be one size larger than the motor's rating. During rapid deceleration and braking, the motor generates a large amount of regenerative energy. To manage this, the planer’s reversing brake employs deceleration braking along with an external braking resistor unit. This allows the excess energy to be dissipated through resistance heating, improving the braking efficiency of the inverter.
3.2 Inverter External Wiring Diagram (see the figure below)
3.3 Inverter Function Parameter Adjustment
To ensure the inverter meets the load and operational requirements, several key parameters must be configured:
3.3.1 Frequency Setting
F01 is the frequency setting function. During commissioning, you can choose 0 for keypad adjustment or 1 for voltage input via terminal [12] (0–10 V). The frequency can be set according to the required operating speed.
3.3.2 Operation Command
F02 is the operation command. It should be set to 1, allowing external terminals [FWD] and [REV] to control the running direction.
3.3.3 Acceleration and Deceleration Time
F07 (acceleration time) and F08 (deceleration time) are both set to 1.8 seconds, depending on actual performance.
3.3.4 Torque Boost
F09 is the torque boost setting. Since the motor often operates at low speeds, F09 is set to around 10 for constant torque characteristics. However, increasing the torque boost may lead to overexcitation at low speeds, potentially causing overheating. It’s important to monitor the motor’s performance during continuous operation.
3.3.5 Frequency Limitation
As a universal motor is being used, the upper frequency (F15) should be set to 50 Hz.
3.3.6 Motor Parameter Settings
P01 sets the number of motor poles to 6, P02 sets the motor power to 37 kW, P03 sets the rated current to 71 A, and P04 is set to 2 for motor self-tuning, which requires the load to be disconnected during setup.
4 Conclusion
After replacing the original DC motor-generator set with an inverter-based system, the B1012A single-arm planer has met all production process requirements. It has significantly reduced energy consumption, improved production efficiency, and made adjustments and maintenance much easier. The retrofit has proven to be a successful and cost-effective upgrade.
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