Cylindrical grinders are increasing productivity when machining non-circular parts. For non-circular grinding workshops, past cam-driven grinding machines or a combination of surface grinders and grinders, these methods have proven to be inflexible in production and more cumbersome to install.
On the other hand, cylindrical grinding machines are versatile in the type of grinding workpiece they can handle, while having the precision and rigidity necessary to reduce production costs in the shop. In addition, the cylindrical grinding machine enables more parts to be machined by installing fewer machine tools in the shop.
The success of non-circular parts grinding on a cylindrical grinding machine depends on the exact machine movement, as this method is an interpolation between the C-axis and the X-axis of the two machine axes. The C axis is the workpiece rotation axis, and the X axis is the grinding head axis. The grinding head moves in and out of the workpiece, following the contour of the contour of the non-circular part. Usually it is opposite to the X axis. At the same time, the workpiece chuck spindle accelerates and decelerates, maintaining a constant load on the grinding wheel to avoid surface defects.
To ensure accurate shaft movement, many cylindrical grinder manufacturers combine static pressure methods, linear motors, high-scoring scales on the X-axis and integral motors, direct-push static cylinders and rotary encoders on the C-axis. . All of this part works together. It can almost eliminate the backlash and small movement of the X and C axes.
Dwight Myers, project bidding manager at Cinetic Landis Grinding, said, “In non-circular grinding, when the machine axis is reversed, the shop should focus on the 'impact movement', for example, a machine with a ball screw, when the shaft is reversed. At the time, it experienced flexibility (jumping and/or deflection). On the other hand, linear motor and static pressure method systems have the rigidity necessary to eliminate this phenomenon."
According to Nelson Beaulieu, grinding product manager at Hardinge's Kellenberger grinding machine, “The static pressure method allows the grinding machine to move very slowly without minor displacements, which can produce tiny back-grain marks on the surface and contour of the part. Beaulieu also points out The static pressure spindle eliminates the spindle reverse error. When grinding above or below the centerline, this error can be revealed by errors caused by fluctuations in the surface of the part and the grinding load. This is usually the case, and he added that the static pressure spindle remains rigid even when the load on it changes.
In addition to hydrostatic bearings, most manufacturers use integral direct drive spindles for the C-axis of cylindrical grinders for non-circular part grinding. Such spindles are directly coupled to the servo motor that drives them. These motors are actually embedded in the rotating shaft and do not require belts or gears. Eugene Supernor, head of the spindle division of Bryant Grinding Machines, a division of the Vermont Machine Tool (machine tool) division, says belts or gears will shape the accuracy of the shaft.
However, not all manufacturers use hydraulic spindles, and Studer is equipped with a direct drive spindle with high-precision ball bearings for its cylindrical grinding machines. Hans Ueltschi, National Sales Manager at Studer Cylindrical Grinders, United Grinding Technologies, said the company found that the ball bearing spindles provide increased rigidity in the event of a change in speed, and the process conditions for non-circular parts. The change can make a better response.
The static pressure method, linear motor and direct drive Ren axis can provide accurate motion. It uses special software and CNC to program to synchronize its motion. If the above software is not used, grinding the non-circular parts on the cylindrical grinding machine requires manual programming of the workpiece speed and the change of the roller feed.
In non-circular part grinding, the workpiece speed and the grinding wheel feed must be changed frequently to match the change in metal removal rate. For example, the shop may run three or four different workpiece rotation speeds during the rotation of a non-circular part, and the software must be able to initiate these changes in workpiece speed and roller feed.
The special software package also allows the shop to use high-speed machining technology for non-circular grinding to further optimize the process. In essence, the high-speed machining technique used for grinding is related to changes in the rotational speed of the workpiece that maintains a constant grinding surface length. If the workpiece speed remains constant during non-circular grinding, some parts of the workpiece will turn too slowly and other parts may turn too fast. The area that is rotating too slowly, because the grinding wheel stays on it for too long, showing dents and burns. On the contrary, the city that rotates too fast is deviated due to improper cutting.
Ueltschi explains: “The grinding wheel is used as a cutting tool. When grinding a part, the workshop does not use a fixed feed rate. They accelerate in a straight place and slow down at each corner to maintain stability on the tool. The cutting force. The same is true for high-speed non-circular grinding."
In addition to the problem of maintaining a stable cutting force, non-circular grinding workshops must be able to smoothly transition from one part to the next. For example, two features are to be blended in a part. The appropriate diameter is required between the curved and the plane, as in a punch press.
The lag of the machine tool movement, the problem of the tool or the installation, the reaction time of the software and the programming of the machine tool can all lead to poor quality of the transition between the facet and the part features. However, the poor grinding quality of non-circular parts is often due to the lack of stiffness. This is why almost every external machine tool manufacturer believes that in order to be accurate in non-circular grinding operations, it is necessary to have a rigid machine platform. This platform includes heavy-duty components that are mounted on a base plate that is thermally and mechanically stable.
High Lever Series,High Lever Series Faucet,High Lever Series Mixer,High Lever Series Taps
WENZHOU CHENKAI SANITARY WARE CO.,LTD , https://www.chenkaisanitary.com