DESKTOP MILLING MACHINE WITH OVATE-SHAPED BRIDGE

The desktop milling machine with an ovate-shaped bridge is a desktop milling machine of the computer numerical control (CNC) type having a portion of the bridge or frame structure configured to alleviate bridge deflections and deformations that are caused during the high-speed milling processes. Preferably, the bridge has an ovate arch, or has a rear face having an ovate contour.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to machine tools, and particularly to a desktop milling machine with an ovate-shaped bridge.

2. Description of the Related Art

Micro-scale (and meso-scale) components have generally been produced by conventional machine tools. Since by definition micro components are small, the dimensional tolerance allowances would also be small, thereby creating a high incidence of error when utilizing conventional machine tools to manufacture the micro components. To alleviate these errors, relatively small computer numerical control (CNC) desktop milling machines have been employed to manufacture micro components. The use of these desktop milling machines has greatly reduced manufacturing errors in the production of micro components, saving both time and money. However, the high speed manufacturing techniques performed by the desktop machine produce high-frequency induced loads and temperature rises that can cause distorting resonances in the frame or bridge of the machine.

The major problem that may result from the resonances is that the disturbance set up in the bridge is also easily transferable through relatively weak joints back onto the spindle and tool assembly, which are supported on the bridge, causing deformations. Although such deformations might be slight, they have a high impact on the accuracy of a micro-milling procedure. The effect of this on the already complex dynamics of the spindle-tool system may be enough to cause bad surface quality, chatter, and tool breakage.

Hence, it is important that the bridge has higher natural frequencies and stiffness to resist these deformation resonances. A design that would produce a bridge that has a higher natural frequency than the related art bridges would alleviate the effect of the distorting resonances and would greatly enhance the efficiency of the desktop milling process. Thus, a desktop milling machine with an ovate-shaped bridge solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The desktop milling machine with an ovate-shaped bridge is a desktop milling machine of the computer numerical control (CNC) type having a bridge or frame structure designed to alleviate bridge deflections and deformations that are caused during the high-speed milling processes. In a preferred embodiment, the bridge is formed with an opening for receiving a work piece or micro-component therein during the milling process. The opening is of an ovate or egg-shaped configuration. A second embodiment provides an ovate contour in a vertical wall of the bridge. It has been determined that the ovate design of the bridge creates a structure that has a higher natural frequency than other milling machine bridges and greatly reduces the incidence of bridge-deforming resonances. The front face of the bridge structure supports the high-speed spindle and removable milling tools, as is conventional in the art.

Accordingly, the invention presents a desktop milling machine that is configured to minimize manufacturing errors that may arise during the milling process. The milling machine is stable, rugged and dependable. The invention provides for improved elements thereof in an arrangement for the purposes described that are inexpensive, dependable and fully effective in accomplishing their intended purposes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference toFIGS. 1 and 2, the desktop milling machine with ovate-shaped bridge is generally indicated at10. The milling machine10comprises a bridge or frame structure12, which has a front face12aand a rear face12b.A high speed spindle14is mounted on the front face12a.A work tool16is removably mounted to the high speed spindle14. As is well known, spindle14is preferably selectively vertically adjustable and movable along a controlled axis by any suitable type of vertical mount or mechanism. The work tool16may be one of many types, such as a grinder, polisher, drill, etc. The bridge12comprises three support legs18that are preferably bolted to a platform20. A workpiece holder22is positioned on the platform20and is movable thereon. A workpiece (micro component)24is removably clamped in the workpiece holder. An opening26is cut out of the bridge12, which provides space for manipulating the workpiece holder22and workpiece24in proper alignment with the tool16when performing a milling procedure. The opening26is defined by a continuous wall28and has an ovate configuration. As pointed out above, this configuration has been determined to provide stability for the frame and minimize the effects of bridge deformation due to resonance forces produced when performing a milling procedure. As is well known in the art, the workpiece holder22is preferably mounted on an X-Y table, allowing for two-dimensional horizontal adjustment of the workpiece24with respect to the milling machine.

In the embodiment as shown inFIG. 3, the bridge30is L-shaped in profile, having a work-holding platform32. A bridge wall34is mounted on the platform32and rises vertically therefrom. A high-speed spindle14(shown in phantom lines) is mounted on the front face of the bridge wall34. The rear wall, or rear face of the bridge wall34, is of an ovate configuration36. As in the previous embodiment, high-speed spindle14is preferably selectively vertically adjustable and movable. Further, as in the previous embodiment, the platform32preferably supports an X-Y stage for selective horizontal movement of the workpiece along two orthogonal axes.