Abstract: This article introduces the production process of optical discs, the composition of optical disc manufacturing equipment, the characteristics of DD motors, and their applications in optical disc manufacturing equipment. The advantages of using direct drive servo in this equipment are put forward. The use of direct drive servo will definitely be a development trend in the future, and the use on equipment will become more and more widespread.

Keywords: DD motor, CD production process, CD-R / DVDR equipment, high precision,

The application of DD motor on the DVD / CVD manufacture machine

Abstract: The CD manufacturing technical and the buildup of the CD manufacture machine is introduced. The characteristic and the application of the DD motor in the CD manufacture machine are also introduced. Because of the predominance of direct driver, there will be more and more application of the direct driver in the machine area.

Keyword: DD motor, CD manufacture technical, CD-R / DVDR equipment, high accuracy

Foreword

The synchronization of digital optical discs with the development of the information society is one of the areas with the greatest potential for social development today. With the promotion and popularization of high-definition digital TV, with the birth of digital cinemas, video, audio, and digital movies will develop in the direction of petabytes, so the storage capacity, density, transmission speed, and production speed of optical discs will also be permanent. Endless improvement. The total DVDR disc market capacity in 2006 has reached 3.5 billion. The use of DD motors in DVDR manufacturing equipment has reduced the production cycle of optical discs to 4.5 seconds, and each device can produce 500,000 pieces per month, greatly improving production efficiency and winning market competition.

1 Introduction to disc production technology and equipment

The difference between the “Recordable Disc” (CD-R) and “High-density Recordable Disc” (DVD + R / DVD-R) is that CD-R only needs to be spin-coated and then cured, while DVDR is Need to do double-sided bonding. The difference between the DVD-R and DVD + R processes is that the DVD-R requires an extra "pre-engraving" operation. DVD-R / DVD + R production process: incoming inspection-material safety inventory-plastic drying-injection white film-production line (dye spin coating, metal sputtering, bonding, curing, online testing)-offline testing machine ( Quality inspection)-DVD-R pre-engraving-printing-visual inspection-warehousing-shipment.

      In mass reproduction production, "polycarbonate materials" are often used as materials, and optical discs are produced by injection molding. Features are good transparency, volume stability, impact resistance without magazines. The injection molding machine consists of a mold, a thermometer, and a disc transfer arm. The function of the DD motor is to complete the transmission function on the disc transfer arm. The usual transmission distance is 180 degrees or 90 degrees. The shorter the transfer time, the greater the production efficiency is the increase in the number of discs produced per unit time.

2 DD Motor Product Features

DD motor is literally a direct drive, but in fact it is not an ordinary motor, but a special type of AC motor with a very complicated structure, high precision and high performance. It is called direct drive, because it adopts the direct connection between the rotor and the moving carrier, and no other transitional connections are used in the middle (deceleration mechanism, coupling, etc.).

DD motor structure is in the form of an outer rotor, which is different from ordinary motors with an inner rotor structure. In particular, the radial bearing used by it can bear a certain axial force. The encoder is a photoelectric encoder with high resolution, generally more than 500,000 ppr, and has an origin and limit output. Due to the high-level manufacturing process guarantee and high-precision measurement feedback, the positioning accuracy of this motor can reach the second level. (For example, the absolute accuracy of the DM1B series is 15S, and the repeat positioning accuracy is 2S)

Drive principle: DD motor uses a hybrid structure. The stator part 5 is composed of a permanent magnet 4 and a coil winding 3. The permanent magnetic field circuit 1 and the excitation field circuit 2 generate magnetic force to act on the backlash 7 and cause the mover 6 to rotate in a combined direction. The principle of this part is similar to that of a permanent magnet stepper motor, except that the material and precision required are extremely high. The torque and speed characteristics are also very similar. The holding torque is large, and the running torque decreases as the speed increases.

Why choose DD motor as the disc transfer arm transmission mechanism in DVD manufacturing equipment? This must be explained from its characteristics. First, the gap error is eliminated. Due to the intermediate links of reducers, couplings, gears, belts, or screw rods in ordinary transmission mechanisms, clearance errors are unavoidable, especially for mechanical wear caused by long-term operation. The DD motor can solve the above problems very well. Due to the installation of the DD direct drive, the error is minimized; and its servo characteristics can also correct the error at any time to achieve the optimal control accuracy. Secondly, high resolution and high positioning accuracy. The optional encoder of the DYNASERV DD motor has a high resolution. The resolution of the DR5C is 425,984 PPR. The electrical control accuracy is high, which has exceeded the control accuracy of ordinary servos by an order of magnitude. Because the production is quite precise, the final precision control can generally reach within 5 seconds. Third, high rigidity, compact structure and high use efficiency. DD motors have strong rigidity and have very hard characteristics when combined with loads, which require higher requirements for their drives. The latest DYNASERV driver can provide online gain tuning and resonance filtering. The unique design of the hollow motor not only reduces its own inertia, but also provides customers with more installation forms. The combined mechanical structure will be more compact and the use efficiency is the highest compared to other methods.

3 Application of DD motor products in optical disc production equipment

At present, the application of the CD transfer arm adopts PLC control, that is, the PLC only provides input and output points. After receiving the sensor signal, it outputs a high level to the driver of the DD motor. The driver achieves a rotation of 90 through the internally set command in advance. Degrees, -90 degrees. The following briefly introduces how the GIII driver realizes the internal command rotation function through different switching of input points.

（1) Write a run list inside the driver.

There are many types of GIII drive operation list. It can realize relative position point-to-point operation, absolute position point-to-point operation, Homing function, and change parameters. By switching between different input point codes, different table numbers can be run, and motion control can be easily implemented. On DVD disc manufacturing equipment, it is achieved through the table function. Yokogawa GIII driver has a total of 60 sets of tables that can be set and edited arbitrarily. Figures 5 and 6 show the list of tables that can be written and the detailed settings of the table. Taking the absolute position point-to-point as an example, parameters such as acceleration, deceleration type, acceleration / deceleration time, running speed, and target position can be set to meet the requirements of the equipment.

（2) Input point logic switching

IIIGIII driver has 12 input points which can be used. Its logic and definition can be changed arbitrarily. Functions include servo-on, start, stop, continuous operation, input point selection, etc. as shown in Figure 7. The application here uses input point selection, that is, CODE_1, CODE_2, and so on. The table number to be executed according to the needs, for example, the command executed by the set 004 table is rotated 90 degrees in the forward direction, as long as 3 inpit1, input2, input3 are set. The input point can encode the table selection. 004 corresponds to 100, that is, input3 is high level, and the other is low level, and the table 004 is rotated. The input points of servo-on, start, and stop are also indispensable. After servo-on and then start, this will complete the forward 90-degree operation.

4 Conclusion 

大量 The DD motor that is used extensively on the disc transfer arm, compared with the structure of the reducer + servo motor, not only improves the rotation speed, but also improves accuracy and eliminates backlash. Therefore, more and more DVD disc manufacturing equipment manufacturers will choose the DD motor as the first choice of the transfer arm to shorten the production cycle and produce more disc products in a limited time. In the future, more and more direct drive products will be used in various links of transmission equipment.