What is the scraping method of plain bearing?

1. Before scraping, carefully check whether the journal is smooth, whether there are defects such as rust and bruises, and try to eliminate them if so;

2. Then, check the contact between the journal and the shaft, check the method, coat a thin layer of display agent on the shaft diameter (such as red powder, red oil, etc.), then install the journal in the bearing, rotate two or three times in the positive and negative directions by hand, take out the shaft, check the distribution of the coloring points on the bearing, if the distribution of the coloring points is not normal or cannot rotate at all, you can start scraping.

3. When scraping and grinding, the principle of first heavy and then light, scraping heavy and leaving light, scraping large and leaving small should be adopted according to the situation. For the first few times, the hands can be heavier and scrape off more metal to achieve better contact more quickly.

4. When the contact area reaches 50, it should be scraped gently. After each scraping, wipe the tile surface, then apply the indicator to the journal for verification and inspection, and then scrape according to the contact situation until it meets the technical requirements.

5. Indicator can be used for scraping inspection, but for precision bearings with high requirements for contact points, the final stage of scraping cannot be used. This is because the coloring spots on the bearing are too large after the display agent is applied, and it is not easy to judge the actual contact situation. At this time, the journal can be wiped clean, directly placed in the bearing for checking, and then the shaft can be taken out, and the bright spots on the bearing can be seen, that is, the contact point.

The highlights are then scraped until they meet the technical requirements.

When scraping, it is necessary not only to make the contact point meet the technical requirements, but also to make the side clearance and contact angle meet the technical requirements. Generally, the contact point is studied first, and the contact angle is also taken care of, and finally the side gap is scraped. However, there should be no clear boundary between the contact and non-contact parts, and no marks should be perceptible when rubbing the bearing surface with your fingers.

1. Turn the cast bearing pad to the required size on the lathe, and pay attention to the scraping allowance.

2. Before scraping, you should carefully check whether the journal is smooth, whether there are defects such as rust and bruises, and if so, you should remove it first; After checking the contact between the journal and the shaft, the inspection method: apply a thin layer of display agent on the bearing, then install the bearing on the hollow shaft, rotate it two or three times in the positive and negative directions by hand, remove the bearing, check the distribution of the contact points on the bearing, and then scrape it with a scraper.

3. When scraping and grinding, the principle of first heavy and then light, scraping heavy and leaving light, scraping large and leaving small should be adopted according to the situation. At first, you can use more hands to scrape off more metal so that you can achieve better contact faster. When the contact zone reaches 50%, it should be scraped gently.

After each scraping, wipe the tile surface, then apply the indicator to the bearing for verification and inspection, and then scrape according to the contact situation until it meets the technical requirements. It is also necessary to pay attention to the need to pay attention not only to make the contact point meet the technical requirements, but also to meet the technical requirements when the side clearance and contact angle are met. Generally, the contact point is studied first, and the contact angle is also taken care of, and then the gap between the side is scraped.

However, there should be no clear boundary between the contact and non-contact parts, and no marks should be detected when rubbing the bearing surface with your fingers.

The basic requirements are not only to make the journal and the sliding bearing uniform and fine, but also to have a certain fit clearance.

The contact angle refers to the central angle of the contact surface between the journal and the plain bearing. The contact angle should not be too large or too small. If the contact angle is too small, the pressure of the sliding bearing will increase, and in serious cases, it will cause a large deformation of the sliding bearing, accelerate wear and shorten the service life; If the contact angle is too large, it will affect the formation of the oil film and will not get good liquid lubrication.

The test results show that the limit of the contact angle of Bishu plain bearing is 120°. When the sliding bearing is worn to this contact angle, the liquid moist wisdom plexus slip will be destroyed. Therefore, under the premise of not affecting the compression conditions of the sliding bearing, the smaller the contact angle, the better.

From the theoretical analysis of the friction distance, when the contact angle is 60°, the friction torque is the smallest, so it is recommended that the contact angle of 60° should be used for plain bearings with a speed higher than 500r min, and the contact angle of sliding bearings with a speed of less than 500r min can be 90° or 60°.

The actual contact between the contact journal and the plain bearing surface can be expressed in terms of the actual number of contact points per unit area. The more, finer and more uniform contact points mean that the sliding bearing is better scraped, and vice versa, it means that the sliding bearing is not scraped well. Generally speaking, the finer the contact points, the more difficult it is to scrape.

In production, the contact points should be determined according to the performance and working conditions of the plain bearing, and the following table lists the information for reference: Plain bearing speed (r min) Contact points.

Scraping is a finishing process that uses scrapers, datum surfaces, measuring tools and display agents to measure and scrape while grinding points in a manual operation way, so that the workpiece can meet the requirements of size, geometry, surface roughness and tightness specified in the process. Because the tools used are simple, the versatility is relatively strong, the machining allowance is small, and the accuracy achieved is very high, so it is widely used in the manufacture of machines and tools and the repair of mechanical equipment. Usually, the guide rails, carriage plates, and bearings of the sliding bearings of the machine tool are finished by scraping and grinding.

The main functions of scraping are as follows:

Compensate for part machining, assembly and installation deviations, including size, geometry and relative position deviations, etc.;

The contact point forms a shallow pit on the surface of the workpiece, and can also form an oil wedge to facilitate the formation of liquid dynamic lubrication.

You're talking about a centerless grinder, and it's a Taiwanese type.

Because the front end needs to support the spindle rotation, the scraper is to obtain a good contact surface, and a uniform scraping point is required under the contact surface to store the lubricating oil.

Scraping is for better lubrication and machine accuracy.