Principles and characteristics of various dressing methods for diamond grinding wheels

2020-09-21 1824

Diamond grinding wheels have excellent grinding functions and are widely used in the grinding of difficult to process materials such as industrial ceramics, hard alloys, optical glass, diamond cutting tools, and gemstones. However, diamond grinding wheels have hardness, difficulty in dressing, and simple problems such as blockage during the dressing process, which seriously affect the quality and dressing efficiency of the grinding surface and constrain the use of diamond grinding wheels. This article compares and studies various dressing methods for diamond grinding wheels, and analyzes the dressing principles, characteristics, and application occasions of various dressing methods.

1. Grinding and Dressing Method

1.1 Principle of Grinding and Dressing Method

When dressing, a general abrasive grinding wheel is used to grind against a diamond grinding wheel. The diamond grinding wheel rotates, while the general abrasive grinding wheel also performs feed motion along with the rotating motion. The abrasive particles on the surface of the diamond grinding wheel gradually rotate under the action of friction, which generates a certain squeezing force on the metal bond, causing the bond to crack. With the continuous action of friction, the bond crack further expands, The final adhesive breaks, causing the dull diamond particles to detach from the surface of the grinding wheel, exposing sharp diamond particles and reaching the intention of dressing.

1.2 Characteristics of Grinding and Dressing Method

The primary advantages of grinding and dressing method are: simple structure, convenient operation, short dressing time, stable grinding speed, low grinding cost, but there is impact force in the dressing process, low dressing efficiency, poor dressing accuracy, and more abrasive shedding, making the quality difficult to control. Mainly used for dressing ceramic and resin bonded diamond grinding wheels.

2 Soft elastic trimming method

2.1 Principle of Soft Elastic Trimming Method

The soft elastic dressing method involves placing the sand belt on the sand belt wheel during dressing. During dressing, the diamond grinding wheel rotates at high speed, the winding wheel slowly rolls, and the sand belt gradually moves on the belt wheel. The contact force between the sand belt and the grinding wheel is used to remove the bond between the abrasive particles on the surface of the diamond grinding wheel, and then the purpose of dressing is achieved.

2.2 Advantages of Soft Elastic Trimming Method

Compared with other dressing methods, the soft elastic dressing method is more suitable for dressing metal bonded diamond micro powder grinding wheels. Due to the plasticity of metal and high hardness of metal bonded diamond micro powder grinding wheels, the difficulty of dressing is quite high. The first manifestation is that the abrasive particles on the surface of the dressing are quickly worn out, and the second is that the dressing space of the dressing worker is simply blocked, making the dressing unsustainable. The use of soft elastic dressing method for dressing things - the abrasive belt is always in contact with the dressing wheel with new sharp abrasive particles, which can create an excellent dressing environment and effectively remove the bonding between the abrasive particles on the surface of the diamond grinding wheel. Moreover, during dressing, the grinding force is small and the grinding surface quality is high.

3. Electric spark trimming method

3.1 Principles of Electric Spark Dressing

In the process of dressing the diamond grinding wheel, the grinding wheel rotates at high speed, and the diamond grinding wheel is connected to the positive power supply and the negative power supply of the east-west electricity. Grinding coolant is sprayed between the diamond grinding wheel and the east-west electricity, and the voltage is applied between the east-west electricity and the grinding wheel. Spark discharge is generated between the metal binder of the grinding wheel and the dressing electricity. The high temperature of the instantaneous discharge vaporizes the metal binder, and the metal binder on the surface of the grinding wheel is removed, The diamond abrasive particles are fully exposed to complete the dressing of the grinding wheel.

3.2 Characteristics of Electric Spark Dressing

Online dressing can be completed, making it easy to ensure the grinding accuracy of the grinding wheel. The dressed grinding wheel has low grinding force, high accuracy, and can be completed together with the dressing. However, the speed is slow, and electric discharge dressing of the diamond grinding wheel will change the function of the abrasive particles due to high discharge temperature. Controlling the temperature on the surface of the grinding wheel is the key to electric discharge dressing of the diamond grinding wheel.

4 Laser trimming method

4.1 Principle of laser trimming method

The laser dressing method uses an optical system to concentrate the laser beam into a small spot that acts on the surface of the grinding wheel. Except for a small portion of the laser being reflected, the vast majority of the laser is absorbed by metal binders, and the temperature rises rapidly, resulting in the area illuminated by the laser beam being removed by the vaporization of the metal binder. The removal of binder data generally involves several processes: illumination, absorption, heating, and gasification. When laser repairing grinding wheels, reasonable control of laser power and density can remove diamond abrasive particles and bonding materials from the surface of the grinding wheel together, achieving the intention of the grinding wheel. By adjusting laser processing parameters, it can also selectively remove bonding materials from the surface of the grinding wheel, making the diamond abrasive particles have a certain protrusion height, achieving the intention of grinding wheel sharpening.

4.2 Advantages of Laser Dressing Method

Laser dressing method is a non-contact dressing method, which involves no mechanical force or loss of dressing materials. The laser has a short working time, a small working area, and no damage to diamond abrasive particles and adhesives, ensuring the grinding function of the particles. Moreover, the dressing efficiency is high, and the defect is that the dressing process is messy and the cost is high.

5 Electrolytic dressing method

5.1 Principle of electrolytic dressing method

The electrolytic dressing method is mainly used for metal bonded diamond grinding wheels. During electrolytic dressing, the metal bonded grinding wheel is positively connected to the DC power supply as the electrolytic anode, and the east-west power supply is negatively connected to the DC power supply as the electrolytic cathode. Grinding fluid with electrolytic effect is sprayed between the anode and cathode as the electrolyte, forming an electrolytic circuit between the diamond grinding wheel, electrolyte, east-west power supply, and power supply. During dressing, the electrolyte is allowed to fill the gap between the cathode and anode, The current flows from the grinding wheel through the electrolyte to the dressing wheel. The metal components of the metal bond on the surface of the diamond grinding wheel dissolve in the electrolyte under the action of the electrolyte, and combine with the hydroxide ions in the electrolyte to generate small solids that are taken away by the active electrolyte, greatly reducing the bonding strength of the surface of the diamond grinding wheel. At this time, the dressing function can be greatly improved by using mechanical dressing method. So electrolytic dressing is a composite dressing method that mainly relies on electrochemical action and supplemented by mechanical action.

5.2 Characteristics of electrolytic dressing method

The electrolytic dressing method can conveniently complete the online electrolytic dressing of metal bonded diamond grinding wheels, and can be completed together with the dressing. It is easy to control the cutting condition of the surface of the diamond grinding wheel. The advantages of using electrolytic dressing method to dressing diamond grinding wheels are short dressing time and low grinding heat, avoiding the decrease in the service life of the diamond grinding wheel due to high dressing temperature and grain carbonization. The disadvantage is that the electrolytic dressing method has low accuracy and high dressing cost, The process is quite messy.

The article originates from:Diamond grinding wheelhttp://www.jm-nanhua.com