Why are machined electronic cigarette accessories deformed?

All machined electronic cigarette accessories will be deformed, but some can be distinguished by the naked eye , Some require tools to find out. Today, I will follow Runji's editor to analyze why the machined electronic cigarette accessories are deformed?

1. Stress deformation of electronic cigarette accessories after processing

After processing, the accessories themselves have internal stress. The distribution of these internal stresses is a relatively balanced state. Relatively stable, but the internal stress changes after removing some materials and heat treatment. At this time, the accessories need to re-balance the force, so the shape changes. This kind of deformation can be solved by heat treatment, stack the accessories that need to be straightened to a certain height, and use a certain tooling to press them into a straight state, and then put the tooling and accessories into the heating furnace together. According to the different materials of the accessories, choose Different heating temperature and heating time. After thermal straightening, the internal organization of the fitting is stable. At this time, the fittings not only obtain higher straightness, but also eliminate the phenomenon of work hardening, which is more convenient for further finishing of the fittings. Castings should be aged, try to eliminate the internal residual stress, and use the method of reprocessing after deformation, that is, roughing-aging-reprocessing.

For large accessories, profiling should be used, that is, the amount of deformation after assembly of the accessories is expected. The deformation amount is reserved in the direction, which can effectively prevent the deformation of the accessories after assembly.

2. Deformation caused when accessories are clamped

When clamping accessories, first select the correct clamping point, and then select the appropriate clamping point according to the position of the clamping point. the clamping force. Therefore, make the clamping point and the supporting point as consistent as possible, so that the clamping force acts on the support, the clamping point should be as close as possible to the processing surface, and the position where the force is not easy to cause clamping deformation is selected.   When there are clamping forces in several directions on the accessories, the sequence of the clamping forces should be considered. For the contact between the accessories and the support, the clamping force should be applied first, and it is not easy to be too large. For the main clamping force to balance the cutting force The tightening force should be applied last.

Secondly, increase the contact area between the accessory and the fixture or use the axial clamping force. Increasing the rigidity of fittings is an effective way to solve clamping deformation, but due to the shape and structure of thin-walled fittings, they have low rigidity. In this way, under the action of clamping force, deformation will occur.

Increase the contact area between the accessories and the fixture, which can effectively reduce the deformation of the accessories when they are clamped. For example, when milling thin-walled parts, a large number of elastic pressure plates are used to increase the force-bearing area of the contact parts; when turning the inner diameter and outer circle of thin-walled sleeves, whether a simple split transition ring or an elastic mandrel is used. , the whole arc jaws, etc., are used to increase the contact area when the accessories are clamped. This method is beneficial for carrying the clamping force, thus avoiding deformation of the fitting. The axial clamping force is also widely used in production. The design and manufacture of a special fixture can make the clamping force act on the end face, which can solve the bending deformation of the accessories due to the thin wall and poor rigidity of the accessories.

3. Deformation caused by accessories processing

The accessories are elastically deformed in the direction of the force due to the cutting force during the cutting process. The phenomenon of letting the knife is often said. Corresponding measures should be taken on the tool to deal with such deformation. The tool is required to be sharp during finishing. On the one hand, it can reduce the resistance formed by the friction between the tool and the accessories, and on the other hand, it can improve the heat dissipation capacity of the tool when cutting accessories, thereby reducing the number of accessories. residual internal stress.

For example, when milling the large plane of thin-walled accessories, the single-edge milling method is used, and the tool parameter is selected to be larger. Large entering angle and large rake angle, the purpose is to reduce cutting resistance. Because this tool cuts lightly and reduces the deformation of thin-walled accessories, it is widely used in production.

In the turning of thin-walled parts, a reasonable tool angle affects the cutting force during turning, and the turning The thermal deformation of the parts, the micro quality of the surface of the parts are all crucial. The size of the rake angle of the tool determines the cutting deformation and the sharpness of the rake angle of the tool. If the rake angle is large, the cutting deformation and friction will be reduced, but if the rake angle is too large, the wedge angle of the tool will be reduced, the strength of the tool will be weakened, the heat dissipation of the tool will be poor, and the wear will be accelerated. Therefore, when turning thin-walled parts of steel materials, high-speed tools are used, with a rake angle of 6° to 30°, and a carbide tool with a rake angle of 5° to 20°.      The clearance angle of the tool is large, the friction force is small, and the cutting force is correspondingly reduced, but the excessive clearance angle will also weaken the strength of the tool. When turning thin-walled parts, use a high-speed steel turning tool with a clearance angle of 6° to 12°, a carbide tool with a clearance angle of 4° to 12°, and a larger clearance angle for fine turning and rough turning. Take the smaller rear angle. When the inner and outer circles of the thin-walled parts of the car are used, take the larger main declination angle. The correct selection of tools is a necessary condition to deal with the deformation of accessories.

The heat generated by the friction between the tool and the accessories during processing will also deform the accessories, so high-speed cutting is often selected. . In high-speed machining, since the chips are removed in a short time, most of the cutting heat is taken away by the chips, which reduces the thermal deformation of the accessories; secondly, in high-speed machining, due to the reduction of the softened part of the cutting layer material, the It can reduce the deformation of accessories processing, which is beneficial to ensure the size and shape accuracy of accessories. In addition, cutting fluid is mainly used to reduce friction and reduce cutting temperature during cutting. Rational use of cutting fluid plays an important role in improving tool durability, surface quality and machining accuracy. Therefore, in order to prevent the deformation of accessories during processing, sufficient cutting fluid must be used reasonably.

Using a reasonable amount of cutting during machining is the key factor to ensure the accuracy of accessories. When processing thin-walled accessories with high precision requirements, symmetrical processing is generally adopted to balance the stress generated on the opposite sides and achieve a stable state, and the accessories are flat after processing. However, when a large amount of cutting is adopted in a certain process, the accessories will be deformed due to the unbalance of tensile stress and compressive stress.

The deformation of thin-walled parts during turning is multi-faceted, the clamping force when clamping parts, when cutting parts The cutting force and accessories hinder the elastic deformation and plastic deformation of the tool during cutting, which increases the temperature of the cutting area and causes thermal deformation. Therefore, when roughing, we need to take a larger amount of knife and feed; in finishing, the amount of knife is generally 0.2 ~ 0.5mm, and the amount of feed is generally 0.1 ~ 0.2mm/r, or even smaller , The cutting speed is 6 ~ 120m/min, and the cutting speed should be as high as possible when finishing, but it is not easy to be too high. Reasonable selection of cutting amount, so as to achieve the purpose of reducing the deformation of accessories.

4. The material and structure of electronic cigarette accessories will affect the deformation of accessories

The size of the deformation is proportional to the complexity of the shape, aspect ratio and wall thickness, and is proportional to the rigidity of the material proportional to stability. Therefore, when designing accessories, the influence of these factors on the deformation of accessories should be minimized.

Especially in the structure of large accessories, the structure should be more reasonable. Before processing, the defects such as hardness and looseness of the blank should be strictly controlled to ensure the quality of the blank and reduce the deformation of the accessories caused by it.