Common Faults And Solutions When Turning Threads

Threads are formed on the surface of a cylindrical work piece, along a helix, with continuous bulges and grooves with the same profile. In the machinery manufacturing industry, threaded parts are widely used. Using turning method to machine threads is a commonly used processing method.

In the actual turning thread, due to various reasons, resulting in movement between the spindle to the tool, in a certain link there is a problem, causing the turning thread when the fault, affecting normal production, should be resolved in a timely manner.

Common faults and solutions for turning threads are as follows:

First, knife failure analysis and solutions: the reason is that the car knife installation is too high or too low, work parts are not secure or the car knife wear is too large.

1. The car knife is installed too high or too low too high, then eat the knife to a certain depth, the rear knife face of the car knife against the work piece, increase friction, and even bend the work part, resulting in the phenomenon of gnawing knife; The center of the work tool, coupled with the cross-bar and nut gap is too large, resulting in the depth of the knife constantly automatically tend to deepen, so as to lift the work piece, there is a knife at this time, should adjust the height of the knife in time, so that the tip of the knife and the shaft of the work piece is equally high (can use the tail seat top pair knife). In rough and semi-fine vehicles, the tip position is about 1% higher than the center of the workpiece (D indicates the diameter of the machined workpiece).

2. The rigidity of the workpiece itself can not withstand the cutting force when turning, thus producing too much deflection, changing the center height of the knife and workpiece (the workpiece is raised), forming a sharp increase in cutting depth, the emergence of a gnawing knife, at this time should be the workpiece clamped firmly, can use the top of the tail seat, etc., to increase the rigidity of the workpiece.

3. Excessive knife wear caused by increased cutting force, top bending work parts, the appearance of gnawing knife.

Second, the fault analysis and solution: the reason is that when the screw turns a turn, the work piece has not turned the integer turn caused.

1. When the lathe screw pitch and work piece pitch ratio is not a full multiply, if the use of open open and close nut, the bed saddle shake to the starting position, then, close the closing nut again, there will be a car knife tip is not in the previous knife out of the spiral groove, resulting in arbitrary buckle. The solution is to use the forward and reverse vehicle method to return the knife, that is, at the end of the first stroke, do not lift the open and close nut, the knife along the radial exit, the spindle reverse, so that the knife along the vertical return, and then the second trip, so that in the course of reciprocity, because the transmission between the spindle, screw and knife frame has not been separated, the knife is always in the original spiral groove, there will be no buckle.

2. For turning the bed screw pitch and work piece female distance ratio into a full multiplied thread work and screw are rotating, lift open and close the nut, at least wait for the screw to turn around, in order to close again Open and close the nut, so that when the screw turns a turn, the work piece turns an integer times, the car knife can enter the previous knife car out of the spiral groove, there will be no buckle, so that you can use the open open and close nut, manual retreat. This fast retreat is conducive to increasing productivity and maintaining the accuracy of the screw, while the screw is also safer.

Third, the pitch is not correct fault analysis and solutions:

1. The reason for the incorrect thread length is that the hanging wheel is not matched properly or the handle of the in-box is not in the right position, the position of the handle of the in-box can be re-checked or the check-in wheel.

2. The local incorrect reason is due to the pitch local error of the bed screw itself (generally caused by wear), the screw can be replaced or repaired locally.

3. The reason for the uneven pitch on the thread's full length is: the axial movement of the screw. The axis of the spindle is moving in a direction. The opening and opening nuts of the slip box have different shafts from the screws and cause poor meshing.

4. The reason for the appearance of bamboo tattoos is caused by periodic errors in gear transmission from the spindle to the screw, such as the gears in the hanging wheel box, the gears in the incoming box due to themselves, manufacturing errors, or local wear, or the gear on the shaft installation eccentricity caused by the rotation center is low, resulting in uneven rotation of the screw, driving the tool movement of the periodic uneven, resulting in the appearance of bamboo stripes, can be repaired with error or wear gear.