Discussion on the "Rail Biting" of Horizontal Directional Drilling RIGS

1. "Rail biting" caused by the guide wheels of horizontal directional drilling RIGS

The guide wheel of the horizontal directional drilling rig is an important part of the traveling device. Whether its installation position is correct or not has a great impact on the service life of the traveling device. Under normal circumstances, the tracks should be wound in the middle of the guide wheels. Except for a brief lateral shift when turning, the tracks generally do not slip sideways. However, if the guide wheels are skewed, the tracks will be subjected to a component force in the non-skewed direction, causing them to move axially and thus resulting in the "rail biting" phenomenon. The direction of the guide wheel's inclination varies, and so does the location where the guide wheel "bites the rail". If the guide wheel tilts in the horizontal plane, "biting the rail" will occur in front of the guide wheel. If tilting occurs in the vertical plane, it usually happens as "rail biting" above and below the guide wheels. In severe cases, it can cause the front support wheels to drop off the edge. When both types of tilting exist simultaneously, the "eight-shaped rail biting" phenomenon will occur. It can be seen from this that whether the installation position of the guide wheel is correct or not has a great impact on whether the track "bites the rail".

The main factors influencing the installation position of the guide wheels in horizontal directional drilling are:

(1) The symmetry of the centerlines of the circular holes of the pins installed at both ends of the guide wheel shaft exceeded the tolerance, resulting in the longitudinal centerlines of the guide wheel not coexisting with those of the track frame after assembly.

(2) The centerlines of the circular holes of the pins installed at both ends of the guide wheel shaft are not parallel, causing the guide wheel to tilt after installation.

In addition, if there are processing defects in the guide wheels, it can also cause "rail biting". For instance, axial offset occurs during the processing of the middle shoulder of the guide wheels, and the diameters of the raceways on both sides are different, resulting in different tension forces on the tracks on both sides. The tracks are prone to migration, and the generatrix of the raceways is not parallel to the axis of the track pins, thus causing local side sliding of the tracks.

2. "Rail biting" caused by the idler wheels of horizontal directional drilling RIGS

The function of the idler wheels of a horizontal directional drilling rig is to transfer the weight of the machine to the tracks. During the machine's operation, it not only rolls along the track surface of the tracks but also clamps the tracks to prevent them from slipping laterally. When the machine turns, it also ensures that the tracks slide laterally on the ground. The idler wheels are divided into single-sided and double-sided types. Taking the ZD1245 horizontal directional drill as an example, there are a total of 18 idler wheels, all of which are single-sided idler wheels. Multiple single-sided idler wheels jointly form a raceway, and the tracks roll on the track. When the rail busbar does not coincide with the centerlines of the drive wheels and the guide wheels, it will cause the idler wheels to "bite the rail".

The main reasons for the "rail biting" of the horizontal directional drilling support wheels are:

(1) The fixing bolts of the idler wheels are loose, causing the axial position of the idler wheels to change or skew.

(2) The middle flange of the idler wheel was offset during processing.

(3) When the raceway generatrix is not aligned with the axis of the track pin, the track slides sideways.

(4) The diameters of the raceways on both sides of the supporting wheels are different.

(5) When processing the idler wheels, the axial dimension of the raceway is too small, causing the gap between it and the track to be smaller than that between the guide wheels and the track, resulting in "rail biting".

3. "Rail biting" caused by the drive wheels of horizontal directional drilling RIGS

The side clearance between the drive wheel and the track of the horizontal directional drill is the largest, and "rail biting" generally does not occur. However, if the centerline of the horizontal directional drill does not coincide with the centerlines of the guide wheel and the idler wheel, it can also cause "rail biting" of the track.

The main reasons for the "rail biting" of the drive wheels of horizontal directional drilling RIGS are:

(1) The perpendicularity between the positioning surface of the gearbox seat installation hole and the axial centerline of the drive wheel exceeds the tolerance, resulting in the centerline of the drive wheel not being perpendicular to the longitudinal centerline of the track frame.

(2) During the processing of the axial dimensions of the gearbox seat, the deviation was exceeded, causing the drive wheels to be not installed properly, resulting in their centerlines not coincident with the longitudinal centerlines of the track frame.

4. "Rail biting" caused by deformation of the track frame of the horizontal directional drilling rig

The track frame of the horizontal directional drilling rig is a rectangular frame structure welded together. The "four wheels" and buffer devices are all installed on it. Deformation of the track frame will disrupt the positional relationship between the "three wheels" and the drive wheels, thereby causing "rail biting".

The main reason for the "rail biting" caused by the deformation of the track frame in horizontal directional drilling is:

(1) The track frame is bent. The bending of the track frame includes its bending in the horizontal plane and the vertical plane. From the perspective of the impact on the overall machine usage, the bending within the horizontal plane has the greatest effect on "rail biting", and it can also cause the entire machine to deviate.

(2) Deformation of the front open crotch of the track frame. One is to separate outward, and the other is to tilt the crotch.

5. "Rail biting" caused by wear of the horizontal directional drill and other reasons

The working environment of the horizontal directional drilling frame is harsh and it is subject to considerable external forces, so it is prone to wear and tear. The main causes of "rail biting" are:

(1) The mating surfaces of the frame installation surface and the track frame are not well fitted, which damages the verticality between the track frame and the frame.

(2) During the operation of the entire machine, foreign objects got stuck between the guide wheels and the track frame, preventing the guide wheels from being adjusted.

In conclusion, the causes of "rail biting" in horizontal directional drilling RIGS are very complex. Not only should problems during processing and assembly be taken seriously, but also regular and irregular inspections and adjustments of the traveling components should be carried out during use to prevent the occurrence of "rail biting". That is: Check the gap between the outer edge of the guide wheel of the horizontal directional drilling rig and the track frame. When it does not meet the requirements, make corresponding adjustments. Adjust the axial position of the horizontal directional drilling rig's idler sprocket and check whether there are any foreign objects between the horizontal directional wheel and the track frame, etc.