Understanding: "Grit Wheel"

definition

An abrasive, a binder, and a loose, disc-shaped, round-shaped, etc., shaped abrasive are mixed by mixing the green compact, drying, and roasting.

A circular bonded abrasive tool having a through hole in the center made of an abrasive, a binder resin, or the like. Grinding wheel is one of the most used and most widely used abrasive tools. When it is used, it can rotate at high speed and can be used for coarse grinding, semi-finishing and grinding of cylindrical, inner circle, plane and various types of metal or non-metal workpieces. Grinding, slotting and cutting.

Overview

Grinding wheel is the most important type of grinding tool in grinding. The grinding wheel is a porous body made by adding a binder to the abrasive, compacting, drying and roasting. Due to different abrasives, binders, and manufacturing processes, the characteristics of the grinding wheel are very different, and therefore have an important impact on the quality, productivity, and economy of grinding. The characteristics of the grinding wheel are mainly determined by factors such as abrasive, particle size, binder, hardness, structure, shape and size. There are many types of classified abrasive wheels.

According to the abrasives used, it can be divided into ordinary abrasives (corundum, silicon carbide, etc.), grinding wheels and natural abrasive superabrasives (diamonds and cubes)

Boron nitride, etc.) grinding wheel;

According to the shape can be divided into flat grinding wheel, bevel edge grinding wheel, cylindrical grinding wheel, cup-shaped grinding wheel, dish-shaped grinding wheel, etc.; according to the bonding agent can be divided into ceramic grinding wheel, resin grinding wheel, rubber grinding wheel, metal grinding wheel and so on. The characteristic parameters of the grinding wheel include abrasive, viscosity, hardness, binder, shape, size, and the like.

Since grinding wheels are usually operated at high speeds, a rotation test (to ensure that the grinding wheel does not break at the highest working speed) and a static balance test (to prevent the machine from vibrating during operation) should be performed before use. After the grinding wheel has been working for some time, it should be trimmed to restore grinding performance and correct geometry.

Precautions

The use of grinding wheels has certain risks. For everyone's safety, the following lists the precautions in use:

Grinding machine is one of the most commonly used machinery and equipment in mechanical factories. Whether it is installed is reasonable and whether it meets safety requirements; whether it is used correctly and whether it complies with safe operating procedures. These problems are directly related to the personal safety of each employee. Therefore, we must pay enough attention to it in actual use.

Precautions during installation

When installing, the safety quality of the grinding wheel must first be tested. The method is to use the Niel Hammer (can also be used with a pen) to tap the side of the grinding wheel. The sound is crisp and no problem.

Positioning Problems The position of the grinder is the first consideration in our installation process. We can only perform other tasks if we choose a reasonable and appropriate position. Grinding machines are not allowed to be installed in places that are directly facing the nearby equipment and operators or people are often in the past. Generally large workshops should be equipped with a dedicated grinding machine room. If it is really impossible to set up a dedicated grinding machine room due to the limitation of the topography of the plant, a protective baffle not less than 1.8m high shall be installed on the front of the grinding machine, and the baffle shall be solid and effective.

Balance problems The imbalance of the grinding wheel is mainly caused by the inaccurate manufacture and installation of the grinding wheel, which causes the center of gravity of the grinding wheel and the rotary shaft not to coincide. The harm caused by the imbalance is mainly manifested in two aspects. On the one hand, when the grinding wheel rotates at a high speed, the vibration is caused, which can easily cause the surface of the workpiece to generate a polygon-shaped chatter. On the other hand, the imbalance accelerates the vibration of the spindle and the wear of the bearing. It will cause the wheel to break and even cause an accident. Therefore, it is required that the sand office building with a straightness greater than or equal to 200 mm should be statically balanced after the chuck is installed. When the grinding wheel is found to be unbalanced after being trimmed or during work, static balance should be repeated.

The matching problem matching problem mainly refers to the installation and matching problems of the chuck and the grinding wheel. According to the standard requirements, the diameter of the grinding wheel chuck shall not be less than 1/3 of the diameter of the installed sand office building, and the corresponding new grinding wheel shall be replaced when the corresponding grinding wheel wears to a diameter of 10 mm larger than the chuck diameter. In this way, there is a matching problem between the chuck and the grinding wheel, otherwise there will be such a situation that the "big horse-drawn car" causes the waste of equipment and materials; "the small horse-drawn cart" does not meet the safety requirements, and it is easy to cause personal accidents. Therefore, a reasonable match between the chuck and the grinding wheel can save equipment and cut materials on the one hand, and meet safety requirements on the other hand. In addition, a pad with a diameter greater than 2 mm and a thickness of 1 mm to 2 mm should be installed between the grinding wheel and the chuck.

Protection problem The protective cover is the most important protection device for the grinder. Its role is: When the grinding wheel is damaged during work, it can effectively cover the debris of the grinding wheel to ensure the safety of personnel. The shape of the wheel guard is round and square, and the maximum opening angle is not allowed to exceed 90°; the material of the guard is steel whose tensile strength is not less than 415N/mm2. When replacing a new wheel, the guard must be securely mounted and the guard must not be disassembled or discarded.

The blocking screen is one of the main protective attachments of the grinder. The opening of the protective cover above the level of the spindle is greater than or equal to 30 (this device must be set. Its main function is to block the fly in the grinding process to avoid injury Operators, it is installed at the positive end of the shield opening, the width should be greater than the width of the grinding wheel shield, and should be firmly fixed on the shield.In addition, the clearance between the circumferential surface of the grinding wheel and the baffle should be less than 6mm.

Bracket problem Bracket is one of the accessories commonly used for grinding machines. Adjustable brackets must be provided for grinding machines with a grinding wheel diameter of 150 mm or more. The distance between the grinding wheel and the bracket should be less than 1/2 of the smallest dimension of the workpiece being ground, but the maximum should not exceed 3mm.

Grounding problems The grinder uses power lines, so the enclosure of the equipment must have good grounding protection. This is also one of the important factors that can cause accidents.

Precautions during use

Side grinding problems:

In the daily use of the grinding machine, we can often find that some operators randomly use the side of the grinding wheel to grind the grinding wheel regardless of the type of grinding wheel, regardless of the type of grinding wheel. This is a violation of the safety operation procedure. behavior. The grinding wheel with working surface in accordance with the regulation should not use the side grinding. The radial strength of this grinding wheel is large and the axial strength is very small. When the operator is too hard, it will cause the grinding wheel to crush and even hurt. This behavior should be prohibited during use.

Positive operation issues:

In daily use, many operators are always accustomed to the operation of the grinding wheel, because it can be used in this direction. In fact, this behavior is a special prohibition in the operation of the grinder. According to the operating rules, when using the grinder to grind the workpiece, the operator should stand on the side of the grinding wheel and must not operate on the front of the grinding wheel to prevent the grinding wheel from flying out or the grinding wheel breaking and flying out of the wound.

Hard operation problems:

In the use of the grinder, some operators, especially young operators, are eager to grind faster and use too much force, which is an extremely unsafe operation. The flatness of any grinding wheel has a certain strength, which may cause the grinding wheel to be broken or even fly out of the wounding. It is also a behavior that should be prohibited.

Common operating problems:

In actual day-to-day operations, there are also cases where someone is rushing to produce tasks and rob time of work. The two people share a single grinder and operate at the same time. This is a serious illegal operation and should be strictly prohibited. When a grinder is not enough, it can be solved by adding a grinder. Absolutely not allowed to share a grinder at the same time.

Precautions during the replacement process

Wear problem:

Any grinding wheel has its own wear and tear requirements. If the wear condition reaches a certain level, the grinding wheel must be replaced. It is not possible to use ultra-abrasive materials in order to save material. This is an extremely unsafe violation. As a general rule, a new grinding wheel should be replaced when the grinding wheel is worn to a diameter 10 mm larger than the chuck diameter.

Validity issue:

The new wheel from the warehouse is not necessarily a qualified wheel, and even a new wheel bought from the manufacturer is not necessarily a qualified wheel. Any grinding wheel has a certain effective period, and it is used in the effective period. It is a qualified grinding wheel; if it is used beyond the valid period, it is not necessarily a qualified grinding wheel. The regulations stipulate that “the grinding wheel should be used within the validity period, and the resin and rubber binder grinding wheel must be subjected to the rotation test after one year and the qualified person can use it”.

Texture issues:

In the course of use, if there is a local crack in the grinding wheel, stop using it immediately and replace it with a new one so as to avoid the accidental crushing of the wheel.

Other matters needing attention

Environmental issues:

The grinder should generally be equipped with a dedicated grinding machine room. It is strictly forbidden to stack inflammable and explosive items near the grinding machine room or grinder to avoid a fire or explosion accident. It is also forbidden to place other parts or articles near the grinder.

Management issues:

The grinder should be specially responsible. If any personnel other than the company wants to grind articles on the grinder, they must be licensed by the full-time person in charge and strictly abide by the rules of safety. It is strictly forbidden that the outsiders will use the grinder without permission. In addition, the replacement of the grinding wheel should also be handled by a person in charge, and it is forbidden for Others to replace or install the grinding wheel without permission.

Shutdown problem:

After the operator stops working, he should close the car immediately. It is forbidden to idle the grinder when it is not used or managed. In addition, the medium and short-wave turbines should be kept clean after use.