Automated Optical Details Washing Complex Used Before Coating The Details In Vacuum Environment
Washing optical components is a complex technological process that combines the sequence of various technological operations: removal of contaminants, rinsing, drying. New-generation equipment is represented by automated washing complex, AKP‑3 model (hereinafter referred to as the complex). It combined in its design the best solutions used in the commercial washing installations of KP‑1, KP‑2 models, RTKP‑1 complex and some others, as well as a number of fundamentally new developments. The complex is designed for finishing washing of optical parts made of quartz glass with a maximum size of 760 Ч 440 Ч 80 mm using aqueous washing solutions before coating in vacuum environment (Fig.1). The main technical characteristics of AKP‑3 complex are given in the table below. The complex consists of a flushing unit; water treatment stations; circulation-filtration units for each wash bath; filter assembly.
The washing unit consists of four washing baths and a drying bath; auto-operator; cartridge carrier and cartridge; loading table (heating chamber) and cartridge carrier unloading table with a cartridge and a part (hereafter referred to as the cartridge carrier); protective enclosure of the working area of the unit; electric cabinet; remote control.
In the segment of manufacturing optics, there are a lot of competitors; therefore OJSC "OS and VT" retains its positions due to the fact that it provides convenience of processing: baths, loading and unloading tables are mounted within a single frame (Fig.2). The first four baths of the unit are designed for washing optical components in detergent solutions and in water. The capacity of the baths is determined from the calculation of large-sized processed parts. Each of the baths has an overflow outlet for draining liquid into the corresponding circulation-filtration unit and distributing pockets with nozzles for supplying purified liquid back to the baths. The baths are equipped with onboard suction devices to remove the vapors of detergent solutions and water, and are equipped with electric heating elements that are installed on the outside of the bath bottoms, temperature sensors and level sensors. The bath bottoms are equipped with drainage pipes with fittings. All baths are thermally insulated.
The destruction of surface films of mud in the liquid occurs as a result of cavitation and directed acoustic flows. The influence of ultrasonic fields on liquid media causes cavitation processes inside . Therefore, the washing process for parts is implemented in such a way that the first and third baths are equipped with ultrasonic radiators with piezoceramic transducers. They are installed on the outer side walls of the baths in a certain order and ensure uniform influence of the ultrasound field in the liquid. Ultrasonic generators support the frequency of ultrasonic vibrations of 40 kHz in the baths, and the power of ultrasonic generators is regulated.
For optical glasses and crystals, the effect of moisture is critical; it leads to a change in optical properties . For complete removal of water from the surface of the part, it is moved to the heating chamber. For the transfer procedure, the fourth bath is equipped with a device for slow lifting the cartridge carrier out of the bath
The product to be washed is installed in a cartridge. The cartridge with a piece is placed in the cartridge carrier. The cartridge carrier has rollers for easy loading and unloading in the unit. The cartridge carrier is manually installed on the loading table, which is also a heating chamber. The part is heated to the temperature of detergent solutions in order to exclude its damage due to sudden temperature changes during transfer from the room to the baths with a detergent solution. The heating chamber consists of a welded body where the infrared (IR) emitters are disposed. The temperature is controlled with the help of sensors installed in the body of the emitters. The heating chamber is thermally insulated.
The cartridge carrier is transferred from the loading table to the baths and to the unloading table by the auto-operator in the automatic mode according to the preset program. The auto-operator automatically grabs the cartridge carrier, smoothly lifts it from the loading table and out of the baths, moves and lowers it to the grips of a swing mechanism in the baths and on the unloading table. The position of the cartridge carrier at each position is fixed by the position sensors.
For effective removal of contaminants from the surface of the part, a swing mechanism is used, reciprocating the cartridge carrier in the vertical plane.
After washing in four baths, the part is transferred to a drying bath, where the remains of moisture are completely removed. The IR-emitters are installed in the bath. The temperature is controlled by sensors installed in the radiator housing. The drying bath is also thermally insulated.
The last position in the washing process of the work-piece is the loading table. Unloading of the cartridge carrier from the unloading table is done manually or with the help of improvised means.
The washing quality of the part is achieved by using specially treated water. The water treatment station provides the necessary water parameters in terms of chemical composition and additive size. Tap water passes through a series of filters: a coarse filter, a softener filter and fine filters. After the fine filters, water is fed into the second bath.
Water for the first and third baths is further purified by passing through the reverse osmosis membrane, deionization unit on mixed resins, decontamination unit, through an additional fine filter, and is used for the preparation of detergent solutions. Water for the fourth bath also passes through a sterilizing filter.
The circulation-filtration systems of the baths are designed to maintain the filtration rating of solutions and water, as well as for economical use of water due to its repeated use. The main components of the circulation-filtration systems are circulating pumps; storage tanks; filters that provide necessary filtration rating; pipelines, manometers. The circulation-filtration system for the fourth bath also contains an additional filter, which provides finer purification, a mixed ion-exchanger and a UV lamp.
The temperature of the liquids in the washing baths can be set from 30 to 70 °C, so the filter housings, pumps and pipelines of the complex are made of heat-resistant plastic or stainless steel.
The air filtration assembly is designed to prevent contamination and dust from entering the final cleaning zone and creating a laminar flow of purified air. The filtration assembly consists of four serial filter modules, connected in a single system and disposed on the top of the frame above the rinsing baths, the drying bath and the unloading table. The purity class of air supplied to the working area of the unit is provided by its forced circulation through the coarse filter and HEPA filter. Laminar air flow is created when passing through a laminar film installed in each filter module.
The washing unit has a protective guard, which ensures the safety of the unit, preventing contamination and dust ingress from the working area of the part washing. The frame of the unit is assembled from an aluminum profile. The baths, countertops, loading and unloading tables, frame plating and other parts that come into contact directly or indirectly with detergent fluids are made of stainless steel. The unit is tightly closed with shields in the upper part along the perimeter, it has removable covers in the lower part, and there are sliding glasses for visual observation of the auto-operator functioning in the middle part. There are two sliding doors at the loading and unloading positions of the cartridge carrier of the unit.
The complex control system and the ultrasonic generators are mounted in the electrical cabinet. The control system provides for the following functions:
• input, change and display of technological parameters,
• movement adjustment on both axes of the auto-operator movement,
• switching on and off of all actuators,
• indication of the sensors status,
• execution of the program for washing parts in automatic mode,
The control system is based on the universal industrial programmable controller of NJ series, which combines the functions of logic control and motion control. The developed automated washing complex is delivered for optical production of FSUE "RI SPA "Luch".