The diamond roller dresser (rotary dresser)is a kind of diamond roller tools for dressing grinding wheel that a working surface with much small grain diamond. The working principle is that

conventional grinding wheels or CBN grinding wheels are forming dressed by the diamond roller dresser installed on the grinding machine, and after dressing the grinding wheel and then grind the parts, so that the contour, precision, size of the diamond roller dresser are copied through the grinding wheel to the surface of the parts to be ground.

2 Diamond roller dresser compared with and single point diamond dresser, features as follows:

2.1 High precision dressing

This is because as the grinding speed increases, the wear of the single point diamond dresser increase, affecting the dressing precision. The tests have shown that the wear of diamond roller dresser is only 1/2000 of that of single point diamond dresser.

2.2 High-efficiency dressing

Compared with single point dressing, the dressing time of rotary dresser is shortened to 1/10 to 1/100. Especially for the large width forming grinding, the rotary dresser is the whole surface contact grinding wheel dressing, and the single point diamond dresser is single point contact, so the dressing efficiency of the rotary dresser is high. When loading and unloading the workpiece on many automation machine tools, it has been to trim the grinding wheel and the dressing time on the production workpiece can be seen as zero. 

2.3 Complex profile

For complex molding surface, it can trim it, but the single point diamond dresser cannot trim it.

2.4 Good quality stability

The diamond roller dresser can complete the complex profile finishing in one time in the shortest time by plunge grinding, to guarantee the precision quality stability and consistency of mass production parts. The single point diamond dresser causes the precision quality unstable due to the fast wear, and there is the screw profile of the workpiece surface.

2.5 Good cost performance

The cost performance of it is much higher than that of single point diamond dresser. However, according to the dressing cost, dressing cycle, dressing efficiency, service life, replacing clamp frequency and processing quality, the cost performance of the  roller dresser is more than 5 times that of single point diamond dresser.

3 Manufacturing technology of diamond roller dresser

At present, there are external plating method, powder metallurgy sintering method and internal plating method for the manufacturing technology of diamond roller dresser.

3.1 External plating method

Although natural diamond is strictly selected before using, it is different and there is unequal height after randomly arranged on the working surface. The diamond rotary dresser produced by this method has low precision and is usually suitable for processing simple profile workpiece without precision requirements. If the workpiece has precision requirements, the dresser needs to be trimmed before using.

3.2 Powder metallurgy sintering method

Apply a thin layer of resin glue on the high strength graphite internal profile, stick a layer of diamond, dry it, fill copper powder, press it and sinter it. The diamond roller dresser produced by the powder metallurgy sintering method is affected by the shrinkage of the metal powder and has low precision. It should be trimmed when using.

3.3 Internal plating method

3.3.1 Random inter-sand method

Randomly distribute the natural diamond on the internal profile of the female mold, and then nickel plating is performed. Put the steel mandrel in the middle of the female mold, and add the filler between the mandrel and the coating layer, and then process the mandrel and remove the female mold. The diamond rotary dresser produced by this method can obtain high precision. The rotary dresser usually does not need to be trimmed, and it is the only method for manufacturing high precision complex profile dresser.

3.3.2 Hand sanding method

 The difference between the hand sanding method and random inter-sand method is that place the diamond manually in a certain direction on the internal profile of the female mold. The hand sanding tool is self-defined, and the working principle is to select natural diamonds adhesive to the injection needle by the negative pressure principle and put the diamonds on the inner wall of the female mold. This method is suitable for the manufacture of larger grain diamond rotary dresser.

Advantages: Evenly placing diamonds and changing the spacing can control the density of the diamond, achieving the ideal surface roughness of the grinding wheel, which is necessary for processing parts with different materials, different hardness and different precision.

Disadvantages: The precision of hand sanding method is not as good as that of the random inter-sand method. The reason is that the thickness of the adhesive layer is usually about 0.005mm, which is the main reason for affecting the accuracy of the diamond roller dresser. Usually, the precision of diamond rotary dresser by hand sanding method is only

±0.005mm. If higher precision is required, should be trimmed.

 4 Selection of raw materials:

The diamond types are mainly natural diamond, synthetic diamond, CVD diamond.  The type selection and the arrangement at the edge determine the service life and performance of diamond rotary dresser. Engineers will choose different types of diamonds according to the customers’ detailed requirements.

1.  Natural diamond
2.  Synthetic diamond
3.  CVD
4. The diamond configuration on the mold

1 CVD Finished product

2 Natural diamond Finished product

5 Applications and classification of the diamond roller dresser

5.1 Forming diamond roller dresser

Select high-quality large grain natural diamond sintered roller dresser

Manually put the diamond according to the requirements of the parts

Repeatedly adjust the positioning accuracy of the diamond dresser

Precisely trim and measure the profile of diamond rotary dresser by professional equipment

This type of dresser can trim the profile of the complex and high precision grinding wheel at one time, and the retention of the profile is good and has a long service life, which is suitable for the forming grinding of mass production of the parts.

5.2 The applicable CNC machines of the diamond roller dresser

CNC dressing technology of dresser can be applied to all grinding fields with flexible CNC control which can easily change the machining process. It can trim various shapes of grinding wheel and is more suitable for small and medium batch processing.

Applications: Gears, threads, bearing journals, valves, engine valves, fuel injection assemblies, engine components, transmission components, etc.

5.3 Diamond roller dresser for gear grinding

Applications:

• Qinchuan YK7220 YK7232A YK7250
• Reishauer
• KAPP

Customized shapes for the root and top of the gear

 Straight line

Arc

5.4 Diamond roller dresser for forming gear grinding machine

   The forming gear grinding machine can trim the required the gear shapes by CNC system, and requires the diamond rotary dresser body to be highly reliable and has good retention of arc to avoid frequent modification of the CNC system. High precision body adjustment before trimming and precise system testing after trimming can provide a stable and reliable rotary dresser. 

Applications:

• Qinchuan YK7332A YK7380 YK73125
• Niles ZE ZP
• HOFLER HELIX
• Gleason
• Kellenberge

5.5 Blade type diamond dresser

   Blade type diamond dresser can be used to trim the straight lines and other complex shapes by CNC control on the grinding equipment without the dressing spindle. Blade type diamond dresser can get good results from processing small internal grinding wheels to larger grinding wheels for camshafts and crankshafts.

6  When choosing diamond roller dresser, consider the following factors.

6.1 Machined workpiece

Mainly includes workpiece name, material, heat treatment state, technical requirements, machining allowance (radial, axial, etc.), and machining accuracy

6.2 Machine tool

To learn about the machine tool manufacturer, machine model, machine type(external cylindrical grinding, surface grinding, crankshaft grinding, bearing grinding, etc.), especially to learn about the application objects of machine tool, processing methods and machining accuracy.

6.3 Grinding wheel

Select the size( outer diameter, thickness, bore diameter) of the grinding wheel and other technical parameters( abrasive, grain size, hardness, bond, linear velocity, etc.)

6.4 Driving equipment

If the machine tool has the driving equipment, pay attention to the size of the diamond rotary dresser ( max diameter, width, bore diameter). If there is no driving equipment for the machine tool, taking into account the dressing clamp, processing method and the size of the diamond rotary dresser.

6.5 Grinding parameters

It includes the linear velocity of grinding wheel, RPM of the workpiece, feed amount, feed speed, dressing cycle, grinding coolant, and etc.

6.6 Dressing position

It should be reasonably selected according to the actual situation.

7 Problems and preventive measures of the diamond roller dresser

 Table 1 Problem analysis and preventive measures

Customized diamond roller dresser:

Provide professional solutions according to customers’ requirements.

Profile degree=R±0.002  R Tolerance=±0.002  R Minimum=0.02MM