The influence of details in the production process of the grinding wheel

The process requirements for grinding wheel manufacturing are very strong, and any omissions and deviations in the manufacturing process may have a negative impact on the quality of the grinding wheel product. When the finished grinding wheel was factory tested, it was observed that there was a fracture phenomenon, the ring was unwound, the structure was loose, the binder particles were uneven, and the abrasive distribution was uneven. Loose tissues, uneven binders, and the occurrence of defects in the ring are all associated with improper manufacturing processes. There are many problems in the process of compounding, molding, firing or curing, car repair, and trimming.

Analysis of the causes of the quality problems of grinding wheels

In general, to do a good job of grinding wheel products, you need to do the following five points:

1. Formulation technology

At present, the common super-hard grinding wheel formulation in China is mainly low-temperature powdered aldehyde resin grinding wheel, which is based on the 180° sintering base. The metal resin grinding wheels at home and abroad are mainly around 400°, the ceramic metal is mainly about 650°, and the metal bonding agent is mainly alloy powder. All of the above are to increase the strength and life of the grinding wheel. Therefore, the formula of each manufacturer should not stay in the past improvement direction. The durability, dry grinding, sharpness and other quality problems should not be improved by adding only copper powder or graphite powder. This will not produce very good results for the whole formula. The formula is actually a very good grinding wheel with three raw materials.

2. Raw material control

The grinding wheel is a complex system composed of a variety of main and auxiliary materials. The main materials are abrasives and bonding agents, and the auxiliary materials include fillers and reinforcing materials.

(1) Abrasive: Abrasive is the main material for grinding in the grinding wheel. At present, the quality of the abrasive material on the market is mixed, and the main performance is as follows: 1 The composition of the abrasive is often qualified, but the physical properties are poor, such as hardness, strength, and self. Sharpness, crush resistance, thermal stability, hydrophilicity, etc.; 2 The particle size composition of the abrasive is disordered, and the difference from the standard is large, and the mesh number is relatively wide.

(2) Bonding agent: In the grinding wheel, the abrasive particles are bonded together by the bonding agent, and the performance of the bonding agent directly affects the performance and quality of the grinding wheel. 1 The quality of powdered aldehyde resin powder is unstable, and the content of free phenol in the resin is high and low. The so-called free phenol is the phenol remaining in the resin, the molecular formula is C6H5OH, the heating time is too long or the grinding wheel is used for a long time to crack the hardened resin, which affects the strength of the grinding wheel; 2 the powdered aldehyde resin powder is not mixed with the urotropine Uniform, the scientific name of urotropine is hexamethylenetetramine ((CH2)6N4). As a hardener for the resin, the amount of urotropine added is insufficient, the hardening of the resin is incomplete, affecting the strength and hardness of the grinding wheel; If it is high, the excess urotropine is not combined with the resin, and it is decomposed and volatilized during the hardening process, so that the pores of the grinding wheel are increased, and the strength and hardness are lowered. The resin and urotropine are mixed unevenly, and the consequence is that the urodose content is too high or too low; 3 the binder powder is too coarse in particle size, it is generally believed that the particle size of the binder is fine, which is also beneficial. Uniform distribution of the binder facilitates sufficient contact of the hardener. If the particle size is too coarse, the molding material is not easily mixed uniformly, which affects the hardness and strength of the grinding wheel. To produce fine-grained grinding wheel products, the binder requires a particle size of a few microns.

3. Manufacturing process problems

The process requirements for grinding wheel manufacturing are very strong, and any omissions and deviations in the manufacturing process may have a negative impact on the quality of the grinding wheel product. When the finished grinding wheel was factory tested, it was observed that there was a fracture phenomenon, the ring was unwound, the structure was loose, the binder particles were uneven, and the abrasive distribution was uneven. Loose tissues, uneven binders, and the occurrence of defects in the ring are all associated with improper manufacturing processes. There are many problems in the process of compounding, molding, firing or curing, car repair, and trimming.

(1) Compounding process: The ingredients are the preliminary preparation of the mixing. The compounding is an abrasive, a wetting agent, a binder, a filler, etc. according to a certain procedure and method, so that the wetting agent, the binder, the filler abrasive and the like are evenly distributed with each other.

The key to the mixing is uniformity, and the forming powder should be achieved; the components are evenly distributed, kept loose, easy to spread, and have good forming properties. In some production plants, the mechanical mixing or manual mixing time is not enough, and the mixing and sieving operations are sloppy, which does not meet the above requirements.

(2) Molding process: the correct operation is to pour the molding powder into the middle of the mold, and then use a special scraper blade to spread the powder in a clockwise direction and compact it so that it is evenly distributed in the mold. The powder and the substrate reach a predetermined size and shape without cracking or delamination. Some employees of the company have no way to operate, resulting in uneven quality distribution, geometrical tolerances and static balance.

(3) Forming or solidification: This is the most critical production process. There are two factors that easily cause quality problems. One is that the temperature difference between the curing oven or the burning pressure is too large; the other is that the way the grinding wheel is placed in the curing oven is improper.

The temperature difference between the oven or the burning pressure is generally measured when the grinding wheel is not installed. At this time, the temperature difference is small, and when the oven or the hot-pressing grinding wheel is mounted on the mold, the improper position of the grinding wheel of the grinding wheel may hinder the flow of the hot air in the oven or the crucible. The temperature difference increases, deviating from the set hardening requirements, so that the curing (hardening) quality of the grinding wheel is not fully guaranteed.

(4) Plastic processing: Some grinding wheels should be repaired after firing or curing to ensure the geometrical dimensions and shape tolerances of the grinding wheel. Some companies have missed the process, and the car has been repaired and sloppy, and the process is not in place.

(5) Process documents and process parameters: The process documents of some small enterprises are incomplete, and the process parameters will not be adjusted according to fluctuations in raw material composition, changes in climatic and environmental conditions or different requirements of users. These problems are often used to produce grinding wheels. It is unstable.

4. Process equipment

(1) Material: When the material comes, the testing equipment is not advanced, the analytical instrument is backward, and the problem cannot be found in time.

(2) Equipment: Production equipment is an important material prerequisite for the production of grinding wheels. Some enterprises lack equipment. If there is no mixing machine, the hydraulic machine has less tonnage specifications, and second, the equipment maintenance is poor, and the equipment cannot be in good condition. Therefore, not only the production efficiency is low, the labor intensity is large, and the product quality is not easy to guarantee.

(3) Tooling: Some enterprises have weak tooling management, no complete account for molds, no personnel to check and accept records in time, no storage space of good size, no storage space of standard size, no mess at the production site put.

5. Management system

(1) Incoming goods inspection (such as raw material approach inspection), process inspection, routine inspection (commonly referred to as factory inspection), confirmation inspection, etc., are all important contents for effective inspection and control of grinding wheel manufacturers. Some enterprises are especially small. The gap between enterprises and small-scale production enterprises is obvious. The main problems are incomplete systems, unimplemented functions, lax management, short control of inspection equipment, and poor quality of inspection personnel. For example: there is no special inspection agency; inspectors often work part-time, and self-produced and self-inspection, it is difficult to strictly control; the inspection system is not perfect, or the system content is too general or general, or from the actual situation of the enterprise; The phenomenon of release from the factory has occurred; management is confusing, the implementation standards are not strict, the inspectors are poorly responsible, the business capability is not high, and misdetection and missed inspections occur frequently.

(2) The inspection equipment is in short supply and the management is poor. The inspection equipment is not complete, microscope, static balancer, dynamic balancer, and other thin-plate grinding wheel end face, radial runout tester, inner diameter gauge, vernier caliper, grinding wheel cutting performance testing machine, etc. Without periodic calibration and calibration, the inspection equipment for the grinding wheel is not only fully equipped, but also requires an effective calibration state, so periodic verification or calibration is required. For example, dynamic balancing machines, instruments, and measuring tools should be inspected regularly. There is also a lack of proper maintenance and maintenance of the static balancer. The surface roughness of the two-axis rolls is required to be within Ra = 0.2 to 1.6 μm.

A well-made grinding wheel is a seemingly simple one. In fact, it is necessary to do a good job and pay attention to details in all aspects. Several indicators for the grinding wheel are: the stability of the grinding wheel, the balance of the grinding wheel, the homogeneity of the grinding wheel, the wearability of the grinding wheel, and the wear resistance of the grinding wheel.