How to find the rotary center of a horizontal machining center

The rotary center of a horizontal machining center is a key reference point to ensure the multi-faceted processing accuracy of the workpiece. Its positioning accuracy directly affects the key dimensions such as the coaxiality of the hole system and the end face distance during the turning process. The alignment of the rotation center needs to be accomplished through systematic measurement and calculation, combined with special tools.

I. Definition and Function of the Center of Rotation

The rotary center of a horizontal machining center refers to the theoretical fixed point where the rotation axis of the worktable coincides with the axis of the spindle, usually located at the geometric center of the worktable surface. Once the mechanical coordinate values of this point in the X, Y, and Z directions are determined, they can be used as a unified reference for subsequent multi-sided processing, enabling the completion of processing on four or even five sides in a single clamping.

Ⅱ. Common Alignment Methods (Taking the standard mandrel + Dial Indicator Method as an Example)

1.Measurement of the X-direction rotation center

Install the standard mandrel on the main shaft and fix the dial indicator on the worktable.

Adjust the position of the main shaft so that the dial indicator returns to zero at the highest point of the core shaft.

Rotate the worktable 180°, bring it close to the mandrel again, and observe the deviation of the dial indicator reading.

Fine-tune the X-axis coordinates and measure repeatedly until the readings at 0° and 180° are consistent.

At this point, the X-coordinate displayed on the CRT is the position of the X-direction rotation center.

2. Measurement of the Y-direction rotation center

Measure by the cooperation of gauge blocks and mandshafts.

Move the main shaft along the Y direction to the predetermined position, and gently insert a hand-held gauge block between the mandrel and the worktable.

Adjust until the gauge block just passes through, and record the y-coordinate at this time.

Calculation formula: Y-direction rotation center = CRT display Y-coordinate (negative value) - gauge block thickness - mandrel radius.

3. Measurement of the Z-direction rotation center

Measure the Z-direction height with a dial indicator at positions 0° and 180° on the workbench respectively.

Move the Z-axis to make the readings of the two measurements the same;

At this point, the displayed value on the Z-axis is the coordinate of the Z-direction rotation center.

Ⅲ. Precautions

The rotary center needs to be calibrated regularly, especially after the machine tool has undergone a collision, maintenance or has been in operation for a long time.

Operators should receive professional training and be familiar with the structure and measurement principles of machine tools.

Automatic alignment can be achieved through macro programs to enhance efficiency and consistency.