High precision customized tools and machinery
In the process of tapping the workpiece in the machining industry, sometimes it is encountered due to unreasonable process (the workpiece with the machined threaded hole is welded and then the end face of the threaded hole is processed), the processing personnel misread the drawing (wrong size) or operation error (Calculation errors, drilling shallow bottom holes, programming errors, and positioning errors in the depth of drilling and tapping threaded holes) and many other factors lead to the phenomenon that the threaded holes on some workpieces are not deep enough after processing. High precision customized tools and machinery
Once such a problem occurs, due to the poor stability of the drilling machine, operators and process technicians often directly install the workpiece to be repaired on the boring machine or milling machine table. After the inner diameter of the threaded hole is corrected, drill the bottom hole to the depth of the pattern, and then repair it with a tap. However, this method can easily cause the operator to “friction cutting” on the original thread in the process of deepening the bottom hole, resulting in damage to the existing thread and affecting the processing quality of the threaded hole.
At the same time, this repair method requires the operator to have a good technical level, and the correction process of the threaded hole takes a long time, and the work efficiency is very low. The cost of repairing it with boring and milling equipment is also relatively high. In addition, if the end face of the threaded hole is not perpendicular to the center line of the threaded hole due to the reprocessing after assembly welding or other reasons, it will inevitably lead to the damage to the existing thread during the secondary drilling of the threaded bottom hole. , which will inevitably lead to the hidden danger of scrapping or degrading the threaded hole of the workpiece. After many discussions and experiments, the author has found a series of tips with relatively fast work efficiency and reliable and stable quality.High precision customized tools and machinery
01 Method for repairing threaded shallow holes on a radial drilling machine
If the workpiece material has high hardness, it can be drilled on a radial drilling machine when repairing its threaded holes. However, it is necessary to first correct the center line of the threaded hole and the center line of the main shaft of the drilling machine as shown in Figure 1, and then directly use the drill to correct the center line of the threaded hole and the drilling shaft of the drilling machine to be coaxial, and use the drill bit and tap according to the required size. Drill and tap shallow threaded holes.
1—Workbench 2—Adjustable screw 3—Workpiece 4—Drilling machine spindle 5—Correction screw
The steps to repair the threaded hole: first, place the workpiece on the adjustable screw that has been arranged on the drilling machine table; secondly, screw the correction screw into the threaded hole to be repaired and tighten it to ensure that the center line of the correction screw The center line of the threaded hole is consistent; then, the main shaft of the drilling machine is close to the correction screw (a gap must be left to prevent the main shaft of the drilling machine from squeezing the correction screw and affecting the correction accuracy), and adjust the adjustable screw to make the correction screw parallel to the main shaft of the drilling machine , gradually adjust and gradually lean to ensure that the parallelism error is not greater than 0.03mm, and a piece of paper can be used to pull the upper and lower parts between the main shaft of the drilling machine and the correction screw to make the force uniform; Install it in the main shaft of the drilling machine, clamp the modified drill bit in the drill chuck, insert the drill bit into the threaded hole to be repaired, observe that the clearance between the shank and the threaded hole is uniform, and drill according to the required size to complete the drilling. After the hole is replaced, the tap screw can be replaced. High precision customized tools and machinery
The production of the modified drill is very simple. It is enough to grind the length of the drill edge of an old drill as far as possible. The straight shank part is evenly ground or 1mm removed, so that there is a 1mm gap between the drilled hole and the original threaded hole, and no damage to the existing thread of the threaded hole will occur.
The accuracy of the calibration screw is high, and its thread part must be coaxial with the straight shank part, and there must be no bending, and its length is generally 3 to 5 times the depth of the thread to be repaired to ensure the calibration accuracy.
02 Method of repairing shallow threaded holes with pistol drills
For larger, heavier and softer workpieces (such as aluminum alloy workpieces), when it is necessary to repair the problem of shallow depth of threaded holes with smaller diameters, a pistol drill can be used to hold the aforementioned modified drill bit to drill directly on it. , and then tap the thread manually (see Figure 2).
03 Conclusion
The method of repairing small threaded holes is very innovative, especially the use of old drill bits and modified drill bits after grinding. The problem. In the actual production process, the repairing problem of shallow threaded holes can be effectively solved. High precision customized tools and machinery
