Reasons that affect the normal use of ball screws

Reasons affecting the normal use of ball screw. One of the reasons for the unsmooth running of the ball screw can be divided into two situations. One is that during shipment, many packing materials and anti-bagging packing ball nuts, and when the screw is packed or arranged with steel balls, there is no proper standard procedure to complete the execution. Foreign objects or other debris and other sundries will block the track of the steel balls, resulting in the packing materials blocking the track, thus affecting the running of the ball screw. Another possibility is that if the ball screw is installed without a brush scraper, the machining chips and dust will easily accumulate in the track and block the steel ball track during machining, thus causing the ball screw to run unsmooth. The internal circulation of the ball screw is realized by the reverser, but what factors will affect the operation of the ball screw when it is running?

1. When the nut is installed, it is inclined or eccentric, which will cause abnormal load on the screw rod and cause unstable voltage when the motor is running. Damage of ball screw during handling.

2. When using lead screw for machining, it should be operated according to strict procedures, especially during early installation. If the installation is not in place, it will affect the working accuracy of lead screw.

3. Whether the axial line of the ball screw nut can be coaxial with the hole of the motor seat will also affect the operation, so pay attention to the details during operation.

4. In addition, the quality of ball screw will also directly affect its accuracy during operation. Pay attention to its quality when selecting screw.

5. Rough surface of ball groove of screw or nut, uneven size or hardness of steel ball, incorrect assembly of return pipe, etc. can cause obstacles in the operation of screw rod.

Ball screw is a kind of high-precision component, its precision is reduced and its life is shortened, so it is necessary to ensure its normal operation.

Accuracy of Linear Guide Rail

1. The accuracy grades of linear guide rail are divided into (walking parallelism, taking the guide rail 100mm long as an example), general grade (unmarked /C)5μm, (H)3μm, precision grade (P)2μm, precision grade (SP)1.5μm and precision grade (UP)1μm according to the use of different machines. Preload the slider. Generally, preloading is divided into medium preloading and heavy preloading without preloading. The greater the preloading, the better the rigidity. Load: Generally, at the beginning of selection, it is concluded that 1/3 of rated dynamic load is the upper limit of practical load. Therefore, it is generally ensured that there is no sinking when it is added to medium preloading. If the guide rail is used up and down, it will play a guiding role. How much the slider rises is related to the screw or other transmission methods used, but not to the slide rail and slider.

2. There are basically three kinds of different brands. Usually, the gap effect of light preloading and medium preloading can affect the walking accuracy, load bearing ability and rigidity of the guide rail. And the guide rail with gap is selected, which can reduce the oscillation and impact caused by reciprocating motion to a certain extent.

3. When loading, the slider won’t sink much, so it should be called elastic deformation. If you want to say how much, no guide rail material is marked now, because it can be neglected.

Classification of Linear Guides

1. Linear guide rail pair is generally composed of guide rail, slide block, reverser, rolling body and holder, etc. It is a new rolling support for relative reciprocating linear motion, which can replace direct sliding touch with steel ball rolling between slide block and guide rail, and the rolling body can complete infinite circulation in raceway and slide block by means of reverser, with simple structure.

2. Small dynamic-static conflict coefficient, high positioning accuracy, good accuracy persistence, etc. Linear guide rail, also known as fine rolling linear guide rail pair, slide rail, linear guide rail, linear slide rail and rolling guide rail, is used for linear reciprocating motion occasions requiring accurate control of walking parallelism of worktable, has higher rated load than linear bearing, can bear a certain torque together, and can complete high-precision linear motion under high load.

3. The function of the linear guide rail is to support and guide the moving parts, and the worktable is driven to move smoothly in a given direction to make reciprocating linear motion by two or four rows of balls on both sides of the guide rail. According to the nature of conflict, linear motion guide can be divided into sliding conflict guide, rolling conflict guide, elastic conflict guide, fluid conflict guide and so on.

Cooling Measures Of Ball Screw Rod In Operation

Screw rod is one of the common product components of large-scale machinery, and its importance has been well known by more and more people. For example, people engaged in industrial mechanization also regard screw rod as a sign that the machine can run stably and normally. It can be seen that its functionality is relatively strong, mainly in the following industries:

In the electronic and mechanical industry, there are many equipments that use screw rods, such as measuring instruments, which have high requirements for measuring accuracy.

In the field of machinery, it has a wide range of products, because in the machinery industry, machinery has high requirements for the processing of each workpiece, whether it is milling machine, grinding machine, drilling machine, lathe, etc., as long as it is used, the precision error is generally below 0.1 mm.

Screw rod is also widely used in the field of numerical control, and many CNC mechanical equipment are large, which can realize automatic processing, but this will not affect its processing accuracy at all; However, with its application, the linear motion and reciprocating motion of CNC machining machinery can be freely converted, and the machining accuracy is also guaranteed.

As we all know, in the process of running the screw rod, the temperature will rise more or less, and the shaft will stretch due to thermal expansion, resulting in positioning accuracy error. Therefore, under the condition of strict positioning accuracy, corresponding cooling measures should be taken:

1. On the premise of meeting product requirements, minimize the pre-tightening amount of screw rod and bearing seat;

2. Choose a large lead as much as possible to reduce the rotating speed;

3. It is very important to choose suitable lubricant.

4. If conditions permit, use lubricating oil or cold air to forcibly cool the screw shaft.

To sum up, the above four measures can prevent the screw from generating high temperature in operation.

What Should We Do If There Is Noise In The Linear Module?

Linear module is a mechanical equipment component commonly used in modern industry. Its appearance can be said to be the crystallization of mechanical development and transformation. It can be seen in the modern military industry, food industry, spraying industry, logistics industry and other industries. This is because it has more significant advantages compared with traditional mechanical systems. For example, its high precision, no empty return but almost zero maintenance (no contact parts), which is difficult for mechanical systems to achieve. What’s more, there are many other advantages such as very high speed, very low speed and high acceleration.

However, there will be some minor problems in the use of any machine, such as noise, and the linear module is no exception!

1. Noise is prone to appear in a dusty environment

Solution: Use a dustproof device when in use. Generally, manufacturers will have stocks; at the same time, when choosing a linear module, you should also give priority to a closed/dust-proof linear module, such as the following one, with a steel belt The screw slide table is more suitable for use in dusty environments. In addition to the dust-proof of the module itself, other dust-proof devices should also be set according to the size of the dust.

2. Different equipment requires different pre-pressure, so noise will also occur;

Solution: According to different equipment, technical adjustment of pre-compression is required before use.

3. The lubricating grease is different, there will be noise

Solution: According to different types of linear modules, select special lubricants.

Inspection And Maintenance Of Ball Screw

The problems caused by ball screw are various, and there is no fixed form. The ball screw shaft or nut sometimes falls off due to its own weight, and when it falls off carelessly, it may cause the loss of product function due to the collision of track or the damage of circulating parts. At this time, it needs to be checked by the company. If there are scars and damages on circulating parts, outer diameter of shaft, track, etc., it will cause poor circulation, which will lead to the loss of product function. Only through correct detection to determine the real cause of the problem, can it be repaired quickly and accurately.

If there is no preparation and inspection before operating the ball screw, there may be faults. In order to reduce the occurrence of faults, how should everyone prepare for the normal operation of the ball screw? For the axis of rotation of ball screw, we should ensure that it is parallel to the linear guide rail of the main base of the machine tool, so as to avoid affecting the machining quality of ball screw due to imbalance.

For single nut ball screw, the gap between screw and nut pair cannot be adjusted. If it is detected that there is a gap between the lead screw and nut pair. First, check whether the thread arcs of the lead screw and nut are worn. If the wear is serious, a complete set of lead screw nuts must be replaced. Whether the axis line of ball screw nut can be coaxial with the hole of the motor seat can also directly affect the movement process of the machine tool.

If noise and vibration are generated in the work of machine tools, the problem of poor lubrication should be considered first after detecting that there is no problem in the mechanical transmission part. After many years of operation of machine tools, the automatic lubrication system of lead screw and nut is often blocked and cannot be lubricated automatically. Grease with high temperature resistance and high speed resistance can be added to bearings and nuts to solve the problem. Grease can ensure the normal operation of bearings and nuts for several years.

How To Choose A Suitable Ball Screw Lead?

If the machine tool produces noise and vibration during work, after detecting that there is no problem with the mechanical transmission part, the problem of poor lubrication must first be considered. After many years of operation, the automatic lubrication system of the screw and nut is often blocked and cannot be automatically lubricated. The problem can be solved by adding high-temperature and high-speed grease to the bearings and nuts. Grease can ensure the normal operation of bearings and nuts for several years.

Ball screw lead selection: The selection of the lead is related to the required motion speed, system, etc. It is usually selected from: 4, 5, 6, 8, 10, 12, 20, the size is larger, and the lead is generally available Choose larger (mainly consider the bearing tooth thickness). When the speed is satisfied, generally choose a smaller lead (to improve the control accuracy); for the occasions requiring high speed, the lead can exceed 20, and the lead can generally be approximately equal to the nominal diameter for a ground screw (Limited by the spiral angle of grinding), such as 32 (32*32), 40 (40*40), etc., of course, It can also be larger (non-grinding, but rarely considered). The larger the lead, the larger the rotation component under the same conditions, the greater the period error and the faster the speed. Therefore, in general high-speed occasions, flexibility is required, and some accuracy requirements are abandoned, and the significance of the clearance requirements becomes smaller (the lead accuracy deviation increases). Therefore, the large-lead screw is generally a single nut.

How To Prolong The Service Life Of Linear Guide Rail?

In the daily use of transmission parts, for the fluid lubrication of sliding guide rail surface, the movement accuracy error caused by the floating of oil film is inevitable. In most cases, fluid lubrication is limited to the boundary area, and direct friction caused by metal contact is inevitable, in which a large amount of energy is wasted by friction loss. On the contrary, because of the low friction energy consumption and the corresponding reduction of friction loss on the rolling surface, the linear guide rail system can be in a high-precision state for a long time. At the same time, due to the small amount of lubricating oil, grease lubrication is enough in most cases, which makes it very easy to design and maintain the lubrication system of machine tools.

There is a slight or negative gap between the slider of the rolling linear guide rail and the guide rail, so the overall rigidity and movement accuracy of the guide rail can be greatly improved. The E2 self-lubricating module product with innovative design of linear guide rail combines the concept of removable type, which makes the linear guide rail extend its maintenance cycle. E2 self-lubricating module is characterized by cost saving, cleanness and environmental protection, flexible installation, convenient disassembly and assembly and easy maintenance. The transparent oil tank design can check the oil quantity at any time, and the corresponding lubricating oil can be selected. It can be used in special environment such as dust, bad weather and water environment.

In order to improve the motion accuracy and accuracy maintenance, linear guideway requires enough negative numbers, which are two contradictory aspects. When the working time is too long, the steel balls begin to wear, and the preload acting on the steel balls begins to weaken, which leads to the decrease of the motion accuracy of the working parts of the machine tool. If you want to keep the initial accuracy of the linear guide, you must replace the guide bracket or even the guide. If the guide rail system has been preloaded. The accuracy of the system has been lost,  and the only way is to replace the linear slider and guide rail.

Causes And Solutions Of Damage To Slide Block Of Linear Guide Rail

First of all, after the slider has been walking for a period of time, it is found that the end cover and end dustproof are deformed or broken, which may be caused by the wrong installation method, which may cause only unilateral stress between the slider and the track, or by external force. Recommendations:

1. The internal defects of the slide block, the solution: change the dustproof system, improve the lubricating oil, increase the amount of lubricating oil and reduce the lubricating time interval.

2. Inappropriate working parameters, solutions: verification of technical calculation, optimization of product configuration and adjustment of installation angle.

3. Wrong load judgment and incorrect number of configuration sliders. Solution: Optimization of product configuration.

Secondly, after using it for a period of time, it is found that the track of the guide rail is indented and the sliding block steel ball is broken, which is mainly caused by overload and the steel ball is separated from the track, causing the steel ball to break and the track to be damaged one after another. Preventive advice:

1. At the end of rated life, solution: replace with new one.

2. Overload, the solution: use a large slider, increase the number of sliders, reduce the external load, improve the installation method, and reduce the unilateral stress.

3. Insufficient lubrication. Solutions: change lubricating oil, increase lubricating oil quantity and reduce lubricating distance.

4. Foreign matter enters the slider. Solution: Improve sealing fittings (double dustproof, lower dustproof, etc.).

What Are The Different Types Of Ball Screws?

The ball screw is composed of a screw rod, a nut, a steel ball, a pre-compression piece, a steering gear, and an anti-skid piece. Its function is to convert rotary motion into linear motion, and the important significance of its development is to transform the bearing from sliding motion into rolling motion. Ball screws are widely used in various industrial equipment and precision instruments because of their low frictional resistance. Transmission components often used in machine tools and precision machinery, whose main function is to convert rotary motion into linear motion, or the rotor into axial repetitive force, and have the characteristics of high precision, reversibility, and high efficiency. Now we mainly introduce the type of ball screws .

1. Heavy-duty ball screw: which can bear large axial load, is suitable for all-electric design machines, air compressors, semiconductor manufacturing devices and forging manufacturing devices, etc.
2. High-speed ball screw : with high-speed feeding, high acceleration, high rigidity, low vibration and low noise. Use and machine tool fast feed, abrasive high-speed cutting center machine and high-speed longitudinal load cutting center, etc.
3. The cooled ball screw:  forced into a whole in the nut, so that the heat source of the low ball screw during high-speed operation is generated by thermal expansion. To achieve high speed and high precision, use high-speed machine tools and high-speed longitudinal load machining machine tools.
4. Nut-rotating ball screw: which integrates ball nut and ball screw to perform linear motion of rotation and linear transmission, is used in semiconductor machinery, industrial robots, woodworking machines, laser processing machines and conveying devices, etc.
5. Self-lubricating ball screw: Self-lubricating ball screw with detachable oil removal device does not need to lubricate pipeline system and equipment, and the cost of oil replacement and waste oil treatment, and greatly reduces the cost of oil products.
6. Silent ball screw:  Ball spacer rings with special grooves are arranged between the balls, which can restrain the noise caused by the collision between the balls and the wear caused by the balls, and make the ball screw move quieter and smoother.

7. There are other grades of ball screws and conversion grade ball screws. There are rollers on the surface of the screw to roll threads. After heat treatment and polishing, it can be assembled into a simple and reasonable price, and it can be shipped quickly.