How is linear guide straightened and what is the principle?

- Oct 06, 2020-

How is linear guide straightened and what is the principle?

First of all, we must base on the theoretical reference line of the reference guide rail as a straight line in space, so the two mutually perpendicular planes (horizontal plane and vertical plane) are aligned separately. During the straightening process, the measurement of the straightness error is also in these two planes. The setting of the coordinate system is the same as the measurement system. Because the guide rail is a rigid part, the deflection is small, and the straightening range cannot be too large. Therefore, the straightness error calculation adopts the least square method during the straightening process, and the least squares center line is used as the benchmark during the straightening process. Straight line. When calibrating the parallelism of the two guide rails, the least squares midline is also used as the benchmark.

 

       The contact between the guide rail and the guide rail base is surface contact, and the guide rail is positioned on mutually perpendicular planes on the base. During alignment, adding material (pad sheet material) to the contact surface of the base is far easier than removing material (grinding or scraping). Therefore, this alignment example uses added material (pad sheet material), but it can only achieve the accuracy of counting threads. (The thickness of the pad sheet material is limited). To achieve high precision, a method of removing material is required. The reference straight line in the straightening process is actually a straight line parallel to the least squares center line of the reference guide rail and passing through the limit point. Since the least squares center line of the reference guide is used as the reference line, for the convenience of adjustment, a straight line parallel to the reference line and passing through the limit point is selected as the reference for adjustment, and then the offset of each measuring point relative to the adjustment reference line is calculated, and the deviation is Adjust the displacement. In this straightening example, the limit point of the vertical surface is the maximum value; the limit point of the horizontal plane is the maximum value of the upper rail or the minimum value of the lower rail (removal of material (grinding or scraping) defines the limit) The points are the maximum and minimum values interchanged). When it is based on a straight line that is parallel to the least squares center line and passes through the limit point, only sheet material is needed to adjust the guide rail.

details as follows: 

       1. Determine the reference guide rail (decided by the technologist or manufacturer) and align it to make the straightness error within the specified range;

       2. Straighten the second guide rail using the above-mentioned method, and use the straightened reference guide rail as the reference straight line to make the least squares center line of the second guide rail and the least square center line of the reference guide rail reach the specified parallelism error.