Matching and preloading of household appliance bearings

Preloading effect
Preloading refers to the use of the bearing in the play by changing the relative position of the inner and outer rings before the bearing is loaded. For household appliances bearings, the main role of pre-tightening is to improve bearing stiffness and suppress vibration noise.
Preload on the bearing noise
When the bearing is subjected to radial load, due to the radial clearance, only part of the steel ball is subjected to load (ABC in the figure), which is called the bearing area, and the other is called the non-bearing area. During the movement of the steel ball from the D to the D' in the non-bearing zone, the magnitude and direction of the combined force of the self-weight and the centrifugal force of the steel ball constantly change, and the steel balls alternately collide with the inner and outer ring raceways, so that abnormal noise is generated inside the bearing. This abnormal sound can be eliminated by preloading the bearing.
However, if the pre-tightening force is too large, the bearing friction increases, the temperature rises, and the noise life of the bearing decreases. Therefore, it is important to choose a suitable preload.
The structure of NSK common dust cover and sealing ring is shown in the figure below. The dust cover (ZZ) is stamped from a steel plate, and the seal ring is made of rubber covered with steel. Among them, the sealing ring is divided into two types: non-contact type (VV) and contact type (DDU, DDW).

For more information and purchase please visit: https://www.supplyforever.com

Learn how to properly operate the engraving machine for quick start

Before working with a stone engraving machine, we should carefully check the spelling of the text in the stone engraving machine engraving project.


Secondly, the engraving is protected: during the engraving process, the engravings are often misplaced, and the engraved objects are damaged during the engraving process.


In order to avoid these problems, we can try the following operations


1. Check if the pliers or chucks selected for CNC engraving are used incorrectly? At the same time, the wear of the pliers or chuck of the stone engraving machine can also lead to the misalignment of the engraved objects. If the pliers or the chuck is too tight, the moment the blade touches the engraved object will also cause the engraving to pop out.


2. For those irregularly shaped engraved objects, the surface seems to have been fixed very tightly, and will also sway back and forth when subjected to downforce. At this point, you can try to put some scrap under the object to increase friction. The other is to keep the package that comes with the item. Although the object is irregularly shaped, the package itself may be very regular and easy to be fixed. Together with a small strip, the irregularly shaped object is very It is easy to be fixed. Or try to fix the part of the rule and discard its irregular parts.


3. If the downforce to be engraved is large, consider whether you must use a cone-shaped nose. If the diamond head of the engraving machine moves too much during the engraving process, the pressure on the side of the tool will cause the engraving. The movement. If you use an incorrect diamond knife, it will cause the same problem. A 90 or 100 degree diamond knife will drill deep into the material, causing the material to move during the engraving process.


4, because the stone engraving machine is often equipped with multi-function pliers or chucks, and they are made of iron, so it is easy to damage the engraved objects or make them fall during the engraving process, then choose some rubber caps or rubber pipes It is helpful to fix the engraved object.


5. For engraving plastic patterns, you can attach the transfer tape to the back of the engraved object, then spray the liquid glue on the side with the tape attached, and then attach it to a surface that can be discarded. This avoids the use of double-sided. Glue, leaving a surface that is difficult to clean. Because the transfer tape is easy to peel and clean. The stone engraving machine uses a special engraved belt. The side of the belt is more viscous than the other side, so the plate can be moved or replaced at will.


Precautions in the processing of stone engraving machine


1. It is forbidden to touch the tip and iron filings with your hands. Iron scraps must be cleaned with iron hooks or brushes.


2. It is forbidden to touch the rotating spindle, workpiece or other moving parts by hand or by any other means;


3. It is forbidden to measure the workpiece and shift the gear during the machining process, and it is not allowed to wipe the workpiece with cotton thread or clean the machine tool;


4. During the operation of the milling machine, the operator must not leave the post, and the machine will find an abnormal phenomenon and stop immediately;


5, often check the bearing temperature, when too high should look for the relevant personnel to check;


6. It is not allowed to open the protective door of the machine during the processing;


7. Strictly abide by the post responsibility system, the machine tool is used by a special person, and the use of others must be approved by the person;


8. It is strictly forbidden to put any items on the beam and the baffle of the machine tool to avoid falling and hurting people;


9. It is strictly forbidden to lie on the machine during the operation, and it is not allowed to sit or lean on the machine frame.