Temperature is one of the most important factors affecting machining accuracy in precision grinding. Even minute temperature changes can lead to dimensional errors, decreased surface quality, and reduced machining stability.
Therefore, understanding the impact of temperature on surface grinding machines is crucial for achieving high-precision machining.
During grinding, the friction between the grinding wheel and the workpiece generates a large amount of heat.
Simultaneously, changes in ambient temperature also affect the machine tool structure. Thermal deformation is one of the reasons affecting machining accuracy.
The machine tool is affected by changes in workshop ambient temperature, motor heating and mechanical friction heating, cutting heat, and cooling media, resulting in uneven temperature rise in various parts of the machine tool, leading to changes in the machine tool's dimensional accuracy and machining accuracy.
A precision double-end surface grinder used for grinding thin steel sheets of 0.6–3.5 mm thickness achieved a dimensional accuracy of mm when machining a 200 mm × 25 mm × 1.08 mm steel sheet during acceptance testing,
with a curvature of less than 5 m over the entire length. However, after 1 hour of continuous automatic grinding, the dimensional variation range increased to 12 μm, and the coolant temperature rose from 17°C at startup to 45°C.
Due to the grinding heat, the spindle journal elongated, and the clearance of the spindle front bearing increased. Therefore, adding a 5.5kW chiller to the machine tool's coolant tank yielded excellent results.
Practice has shown that deformation of the machine tool after heating is a significant factor affecting machining accuracy. High temperatures are generated at the contact area between the grinding wheel and the workpiece, especially during large cuts or continuous machining.
Date-night temperature differences or seasonal variations in the workshop can affect the geometric accuracy of the machine tool.
However, machine tools operate in an environment where temperature changes constantly; the machine tool itself inevitably consumes energy during operation, a significant portion of which is converted into heat in various ways, causing physical changes in the machine tool's components.
These changes vary greatly due to differences in structural design, materials, and other factors.
Machine tool designers should understand the mechanisms of heat formation and temperature distribution patterns, and take corresponding measures to minimize the impact of thermal deformation on machining accuracy.
Temperature variations are significant in most regions throughout the year, and even within a single day.
Consequently, the methods and extent of intervention in indoor (e.g., workshop) temperatures differ, resulting in vastly different temperature environments around machine tools.
Machining workshops generally lack heating in winter and air conditioning in summer, but as long as ventilation is good, the temperature gradient within the workshop remains relatively stable.
The heating season runs from late October to early April of the following year. Machining workshops are designed with heating, but air circulation is insufficient.
The temperature difference between the inside and outside of the workshop can reach 50°C. Therefore, the temperature gradient within the workshop in winter is extremely complex.
During measurement, with an outdoor temperature of 1.5°C and a time of 8:15-8:35 AM, the temperature change within the workshop was approximately 3.5°C. The machining accuracy of precision machine tools will be significantly affected by the ambient temperature in such a workshop.
The surrounding environment refers to the thermal environment created by the various layouts within the vicinity of the machine tool. These include the following four aspects:
1. Workshop microclimate: such as the temperature distribution within the workshop (vertical and horizontal directions). Workshop temperature will slowly change with the alternation of day and night or changes in climate and ventilation.
2. Workshop heat sources: such as sunlight, radiation from heating equipment and high-power lighting. When these are close to the machine tool, they can directly and for a long time affect the temperature rise of the entire machine tool or some of its components.
Heat generated by adjacent equipment during operation will affect the machine tool's temperature rise through radiation or airflow.
3. Heat dissipation: The foundation has a good heat dissipation effect, especially for precision machine tools. The foundation should not be close to underground heating pipes;
if they rupture and leak, they may become a heat source that is difficult to trace. An open workshop is a good "radiator," conducive to temperature uniformity.
4. Temperature control: Using temperature control facilities in the workshop is very effective in maintaining the accuracy and machining precision of precision machine tools, but it consumes a lot of energy.
1. Structural heat sources of the machine tool. Heat generated by motors such as spindle motors, feed servo motors, cooling and lubrication pump motors, and electrical control boxes can all generate heat.
These conditions are permissible for the motor itself, but have significant adverse effects on components such as the spindle and ball screw, and measures should be taken to isolate them.
When the input electrical energy drives the motor, apart from a small portion (about 20%) being converted into heat energy by the motor, most of it will be converted into kinetic energy by the moving mechanisms, such as spindle rotation and table movement;
however, a considerable portion will inevitably be converted into frictional heat during the movement process, such as the heat generated by bearings, guide rails, ball screws, and transmission boxes.
2. Cutting heat from the manufacturing process. During the cutting process, part of the kinetic energy of the tool or workpiece is consumed in cutting work,
while a considerable portion is converted into deformation energy and frictional heat between the chips and the tool, resulting in heat generation in the tool, spindle, and workpiece. A large amount of chip heat is conducted to components such as the machine tool's table and fixtures.
This directly affects the relative position between the tool and the workpiece.
3. Cooling. Cooling is a countermeasure against the increased machine tool temperature, such as motor cooling, spindle component cooling, and basic structural component cooling.
High-end grinding machines often have refrigeration units equipped with their control boxes for forced cooling.
To reduce the impact of temperature on the grinding process, we need to fully utilize coolant to cool the grinding equipment and ensure accuracy.
Simultaneously, preheat the equipment by running it idle before processing to allow the machine tool to reach a thermally stable state.
Secondly, control the ambient temperature, maintaining a constant workshop temperature and avoiding direct sunlight or airflow.
Use air conditioning equipment when necessary.
Temperature is a crucial factor affecting the machining accuracy of surface grinders. Therefore, the YASHIDA 4080APS CNC grinding machine is equipped with a comprehensive cooling system.
By scientifically controlling temperature and optimizing process parameters, machining accuracy and stability can be significantly improved, thereby increasing product quality and production efficiency.
This website uses cookies to ensure you get the best experience on our website.
Español
Portugues
Pусский
العربية
Phone
Comment
（0）