Scientifically classifying the type of barrel plating should be based on the shape and axial direction of the barrel used for barrel plating. The shape of the drum means that the shape of the drum is similar to what the object is. The axial direction of the drum refers to the relationship between the direction of the axis of rotation and the horizontal plane when the drum rotates. According to the difference between the two aspects of the drum, the common barrel plating methods in electroplating production are divided into three types: horizontal barrel plating, inclined barrel plating and vibration plating.
2 horizontal barrel plating
Horizontal barrel-plated drum shape is "bamboo tube" or "column", placed horizontally when in use. The axial direction of the drum is horizontal, so horizontal barrel plating is also called horizontal horizontal barrel plating. The hexagonal drums, chrome-plated cylinders, rod-shaped (or spoke) cylinders, and needle cylinders commonly used in production are all in the category of horizontal barrel plating. Among them, hexagonal rollers are the most widely used. A typical horizontal drum structure is shown in Figure 1.
2.1 Roller cross-sectional shape
Horizontal drums have hexagonal, octagonal and round cross-section shapes. With a hexagonal roller, the part has a large drop when flipping, and the parts are well mixed, so the thickness of the coating is better than that of other shapes. This advantage is more pronounced when the load does not exceed one-half of the drum volume. Moreover, the hexagonal roller parts have a strong effect of polishing each other, which is more conducive to improving the brightness of the plating layer.
2.2 Roller axial
The horizontal direction of the horizontal drum is horizontal. Therefore, when the horizontal roller drives the parts to roll, the running direction of the parts is perpendicular to the horizontal plane, which is beneficial to sufficiently mixing the parts and improving the brightness of the plating layer. Moreover, the vertical operation of the parts also gains an advantage for the loading of the horizontal drum.
For example, it is not uncommon to have a horizontal drum with about 150kg of parts in production, which is unbelievable for other barrel plating methods. Especially in recent years, the length and diameter of the horizontal drum have been greatly developed, and the size and weight of the parts suitable for barrel plating have also increased, and many of the original hanging plated parts can also be barrel-plated. All of these have better demonstrated the superiority of the productivity of barrel plating labor.
Horizontal barrel plating is widely used in barrel plating production with many advantages such as high labor productivity, good surface quality of plated parts, and wide range of applicable parts. The application range of horizontal barrel plating covers most of the electroplating processing of small parts in hardware, home appliances, automobile and motorcycle, bicycle, electronics, instruments, watches, pens, magnetic materials, etc. It is the main force of electroplating processing of small parts. . Therefore, the research focus of the barrel plating technology has always been carried out around horizontal barrel plating. However, due to the closed structure of the horizontal drum, the horizontal plating and plating time is long, the thickness of the plating layer is not uniform, and the plating quality of the parts in the low current area is not good, which makes the application in production suffer.
3 inclined barrel plating
The shape of the inclined barrel-plated drum is "clock" or "bowl", so the inclined drum is also called a bell-shaped drum. The axial direction of the drum is about 40º ~45º the angle of the part is inclined to the horizontal plane, and the name of the inclined barrel plating is derived therefrom.
1-motor; 2-roller; 3-cathode; 4-plating tank; 5-anode; 6-guide trough; 7-lift handle.
Figure 2 inclined submersible barrel plating machine
The inclined barrel plating equipment currently used is called a tilting submerged barrel plating machine (as shown in Fig. 2). The tilting submersible barreling machine was used in the Shanghai area in the 1960s and is popular for its light weight, flexibility and ease of maintenance. In addition, the use of the inclined barrel plating machine is less damaged, and is more suitable for parts that are vulnerable or have high dimensional accuracy requirements. However, the inclined barrel plating machine has a small loading capacity and insufficient part rolling strength, and is inferior to the horizontal barrel plating machine in terms of labor productivity and surface quality of the plated parts. Therefore, the application and development of inclined barrel plating has lagged behind horizontal barrel plating for many years.
4 Vibration plating
Vibration plating is a new small part plating technology that was developed in the late 1970s and used in the early 1980s. It has more outstanding advantages than the conventional barrel plating technology, so it has been rapidly applied and developed as soon as it is published. Domestic vibration plating appeared in the late 1980s, and it has been widely used in the field of small parts plating since the late 1990s.
1-oscillator; 2-vibrator; 3-transmission shaft; 4-feed basket
Figure 3 Schematic diagram of vibrating screen
The shape of the vibrating plated drum is "circular sieve" or "disc", and the movement of the parts inside the drum is achieved by the vibration force from the oscillator. Therefore, the vibrating plated drum is generally referred to as "sand screen" (shown in Figure 3). The vibration axis of the vibrating screen is perpendicular to the horizontal plane, and the moving direction of the parts in the vibrating screen is horizontal.
Vibrating plated vibrating screen structure and vibration axis are essentially different from traditional horizontal drums, so they have a different effect from traditional horizontal barrel plating:
After the upper part of the vibrating screen basket is opened, the closed structure of the conventional horizontal drum is completely broken, and the difference in ion concentration inside and outside the drum is eliminated. Therefore, the defects of the barrel plating caused by the closed structure of the drum are most improved. For example, the deposition speed of the plating layer is uniform, the thickness is uniform, and the plating quality of the low current region of the part is good.
2 By controlling the vibration frequency or amplitude of the vibrating screen, the purpose of controlling the mixing conditions of the parts in the vibrating screen can be achieved, so that the plating thickness fluctuation of each part can be minimized.
3 When electroplating, a large current density is used and mechanical smoothing is performed at the same time, the plating crystal is fine, and the surface brightness is high. 4 parts of the wear, wear and so on are less than other barrel plating methods.
In addition, the cathode conduction is stable during vibration plating, and the phenomenon of clips and card parts is light, and the quality of the parts can be sampled at any time.
However, due to the limitation of the vibrating screen structure and the vibration axial direction, the loading of the vibrating screen is relatively small, and the cost of the vibrating plating equipment is relatively high. Therefore, the current vibrating plating is not suitable for a small single piece and a small number. Electroplating of parts. However, for small parts that are not suitable or can not be used for conventional barrel plating or high quality requirements, such as needle-shaped, small, thin-walled, easy to scratch, easy to deform, high-precision and other parts, vibration plating has unmatched superiority of other barrel plating methods. Sex. Therefore, vibration plating is a powerful complement to conventional barrel plating.
The three methods of barrel plating have their different characteristics, advantages and disadvantages, and scope of application. In the production, according to the shape, size, batch and quality requirements of the plated parts, the accurate and reasonable barrel plating method should be selected to achieve The purpose of saving efficiency and improving product quality. For example, for conventional small parts, the horizontal barrel plating method should be preferred. For small parts that are not suitable or can not be used for horizontal barrel plating or high quality requirements, vibration plating is generally considered. However, vibration plating is not a kind of “all-in-one medicine”. Sometimes, for small parts that cannot be solved by vibration plating, some special plating methods such as basket plating, screen plating or cloth plating can be used.