In production, there are two main methods for using surface grinders to perform form grinding on parts. One method is grinding with a dressed form grinding wheel, and the other is grinding with a special fixture.
1. Grinding punches using a profile grinding wheel involves dressing the grinding wheel to perfectly match the reverse profile of the workpiece, and then using this wheel to grind the workpiece to obtain the desired shape. There are many methods for dressing grinding wheels, the main ones being as follows:
(1) Dressing grinding wheels with diamond
When dressing diamond grinding wheels, the geometric shape of the shaped surface is usually adjusted in segments, but some grinding wheels are dressed in a fully formed shape. This method of dressing grinding wheels is mainly accomplished using various grinding wheel dressing tools. The main grinding wheel dressing tools used in production include tools for dressing angled and curved grinding wheels, universal grinding wheel dressing tools, and template grinding wheel dressing tools.
Horizontal grinding wheel dressing tool. It is mainly used to dress and grind profiled grinding wheels with various angles between 0° and 90°, and then use this grinding wheel to grind the bevel surface of the workpiece.
When dressing a grinding wheel, the position of the diamond tool tip is adjusted by calculating the pad value based on the convex or concave shape and radius of the grinding wheel being dressed.
The horizontal arc dressing grinding wheel fixture can dress concave and convex arcs of various radii, or surfaces formed by connecting arcs.
When dressing non-circular curved surfaces, if the workpiece being ground has a complex shape or a non-circular contour, a specialized template tool can be used to dress the grinding wheel. This tool is a specialized template tool for dressing convex shaped grinding wheels.
The dressing tool for concave forming grinding wheels is basically the same as the template tool for convex forming grinding wheels, but the contact point of the template used should be pointed.
When using the grinding wheel dressing tools described above, it is important to ensure that the diamond tool holder is firmly clamped and never loose.
(2) Using rollers to press the grinding wheel
The extrusion roller has the same profile dimensions as the part. Its circumference has radially spaced straight and oblique grooves, 1.5–2.5 mm wide and at least 2.5 mm deeper than the lowest point of the formed section. These grooves primarily function as cutting edges and can accommodate extruded abrasive particles. The material forms a 10°–15° angle with the extrusion roller's centerline. One or two straight grooves contain embedded iron sheets. After extrusion finishing, these iron sheets are also shaped and can be used to inspect the ground profile and forming grinding wheel or reverse roller. The roller diameter is typically Φ50–60 mm.
A pressing grinding wheel tool mainly consists of two centers. These centers are driven by an electric motor via pulleys or gears. As the rollers gradually press against the grinding wheel, the pressure forces the wheel to eventually achieve the desired shape.
When using a pressing grinding wheel tool, it is mounted on the magnetic worktable of a surface grinder. During installation, the axis of the roller must be parallel to the axis of the grinding wheel.
Furthermore, to dress grinding wheels, both a dressing wheel and a diamond dressing wheel can be installed simultaneously on a conventional surface grinder. In this case, the diamond cutter can be used without a fixture, instead employing a template. The workpiece can then be ground using the dressing wheel created with the diamond cutter according to the template. However, this setup should include a tracker. The interaction between the diamond cutter and the tracker allows them to rotate through the same angle simultaneously, enabling the creation of satisfactory profiles even for curves that are difficult to dress.
2. Grinding using a fixture
When grinding a workpiece, it can be clamped in a special fixture under certain conditions. During the machining process, the workpiece is ground in a fixed or continuously changing position to obtain the desired shape. Commonly used grinding fixtures include: precision vises, sinusoidal magnetic tables, sinusoidal indexing fixtures, universal fixtures, rotary magnetic tables, and center hole clamps. This grinding method is generally performed on a surface grinder.
In production, in order to ensure the quality and efficiency of grinding, a combination of shaped grinding wheels and fixtures is generally used, which can greatly reduce the manufacturing cost of parts.
3. Conversion of dimensions in profile grinding processes
During profile grinding, operators need to convert the design dimensions on the drawings into the process dimensions for profile grinding. This is because the dimensions of the parts in the tooling are generally marked according to the design datum, while the construction datum used in profile grinding is often different from the design datum. However, due to the different machining methods for different types of parts, the requirements for converting profile grinding process dimensions also vary.
