Application of Simphoenix Inverter to CNC Engraving Machine

The spindle system is a very important component for the CNC engraving machine, which has a crucial impact on the performance of the complete machine. The inverter as a key part in this system is more indispensable. This paper mainly introduces the application of the inverter to the spindle driving system on CNC engraving machine.

I. Introduction

Nowadays, the CNC engraving machine gradually becomes a necessary and professional tool for the production in various industries. Meanwhile, with the development and applications of the CNC control technology tied in with the high-performance inverter controller and the servo drive equipments in each production, it’s increasingly going to the mainstream configuration in current engraving industry.

     The spindle system is a very important component for the CNC engraving machine, which has a crucial impact on the performance of the complete machine. The inverter as a key part in this system is more indispensable to the machine. This paper mainly introduces the application of the inverter to the spindle driving system on the CNC engraving machine.

II. Components of the engraving machine and its working principle

     Currently, the mainstream CNC engraving machine is composed of three parts: computer, controller and the main body of the machine. Its working principle is using the dedicated engraving software equipped in the computer to do pattern design and typesetting. Its information will be transmitted from the computer to the controller of the engraving machine and then turned into pulse signals by the controller to drive the stepping motor or servomotor, so that the engraving feed on the X, Y, Z axes in the main body of the machine can be located. Meanwhile, the controller starts the inverter and the spindle motor will be activated to make the engraving head cutting, drilling and milling with high-speed rotating on the processing material fixed in the operating platform. Then various plane or 3D anaglyph pictures and words designed in the computer can be engraved, which achieves the automated engraving operations. Furthermore, it can be used by collocating with different tools according to different processing materials and process requirements.

III. Spindle control system of CNC engraving machine  

The spindle system is a key component of the CNC engraving machine. Its performance has a crucial impact on the whole machine.

The spindle system in the CNC engraving machine is required to adopt infinitely variable speed, which is currently achieved by adopting the inverter to drive asynchronous AC motor. The spindle motor usually uses a double-speed brushless water-cooled motor with advantages of low noise and strong cutting force. Its running speed ​​is generally within 0 ~24000r/min, corresponding to the inverter operational frequency within 0 ~ 400Hz. In order to improve working efficiency, a large engraving machine always contains more than one spindle heads, which makes one inverter driving multiple spindle motors to work.

     SIMPHOENIX Inverter endowed its unique and superior performance and excellent cost satisfies spindle requirements such as wide range of speed, great stability of rotating speed, large overload capacity, big torque in low peed, short acceleration and deceleration time and other performance features. Therefore, it occupies a large share in the domestic engraving machine market.

     For instance, C300 series non-inductive and vector-type inverter for small power has advantages of compact size and high cost performance, usually applied to the engraving system with spindle power less 3.7KW. Moreover, E380 series inverter in general type and H320 series inverter in high frequency type are suitable for large-power spindle. They have advantages of large power and torque stabilization in cutting, usually applied to the engraving and milling system with the power of 5.5KW or more.

IV. Wiring diagram of spindle system and the inverter parameter settings

The power supply system of the engraving machine includes single-phase 220V and three-phase 380V voltages. Most models use the voltage of single-phase 220V for power supply.  The electrical wiring methods can be divided into two following ways according to different frequency source:

1.  Method given by the spindle frequency source for Analog quantity

The inverter frequency source adopts CNC system to output 0 ~ 10V analog signals, corresponding to the operating frequency of 0 ~400Hz. In this way the spindle can get stepless speed variation and change its cutting speed in real time according to different engraving objects or carving craft. This way is widely used in the engraving with high and medium quality, strictly requiring good and fine engraving processing.

Wiring installation diagram of the inverter is shown as follows:  

VC2/GND accepts 0 ~ 10V analog signals outputted by the controller. The voltage value should be proportional to the corresponding speed frequency range of the inverter parameter settings. FWD/CM is a forward signal of the inverter. When the signal is sent, the output relay on the controller will do actions—the normally open contactor of the replay will close and respond signals to the inverter. L1 and L2 are power inputs of the inverter. If the inverter chooses three-phase input wiring, it only needs to connect R, S and T terminals. TA, TB and TC are outputted by the inverter relay, usually selecting the inverter fault alerting output to connect to  the engraving machine controller or external failure indication circuit.

When the inverter is selected to E380 model, the main functional parameters are set as follows:

Note: Some function codes are not applicable to other machine models such as C300 Series and H320 Series. It requires selecting corresponding function parameter values according to the same function code meaning to set. 

2. Method given by the spindle frequency source for multi-speeds

     Users should set spindle running frequencies in the inverter parameters in advance according to processing requirements of the engraving machine. When the CNC system needs different spindle frequencies, the engraving controller will output multichannel digital signal, and the running frequency will be set in accordance with the corresponding inverter in pre-set compound mode. It’s able to quickly respond to and meet requirements of the spindle speed in the engraving program written by the user, which makes the engraving get on best effects. In this way the spindle will run without stepless speed variation, so only some fixed frequencies can be worked. It’s generally applied to low-level engraving processing and machines. 

Wiring installation diagram of the inverter is shown as follows:

FWD/CM is a forward signal of the inverter. The controller of the machine sends the signal out to start the spindle motor. X1/X2/X3/CM are digital signals in multi-speed selection. Output contacts without source are connected to the controller. Then the inverter runs according to frequencies selected through different combined signals of X1, X2 and X3.

 When the inverter is selected to E380 model, the main functional parameters are set as follows:

On the occasion that users need short deceleration time, it can connect the brake resistor between P+/PB of main circuit terminals as required. When in selecting matching models, the brake resistor power can be referred to the power level of machine in attached operation manual.

V. Classification and industrial application of the engraving machine

In terms of applications, CNC engraving machines can be divided into timber engraving machine, stone engraving machine, advertising engraving machine, cylinder engraving machine, craftwork engraving machine and so on.

1. The timber engraving machine is mainly used for wood processing to make it with more aesthetic value.

2. The stone engraving machine can engrave calligraphy and painting on the stone, pottery and ceramic tile.

3. The advertising engraving machine is widely applied to engraving various signage, organic glass, stone doorplate, 3D billboard, decorative gifts and so on.

4. The cylinder engraving machine also called 3D engraving machine can do engraving on the surface of cylindrical materials.

5. The craftwork engraving machine is known as jade engraving machine. It owns advantages of high precision, slow engraving speed and small-size table board, which is suitable for fine craftwork engraving.

VI. Summery

Domestic manufacturers of CNC engraving machine are mainly distributed in Jinan of Shandong, Hefei of Anhui, Jiangsu, Zhejiang and Shanghai. Among these, SIMPHOENIX inverter occupies large share in this fierce engraving machine market. SIMPHOENIX inverter provides the engraving machine industry with most stable and guaranteed spindle power, contributing its strong supporting to the booming of engraving machine market