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We propose several quick and safe methods of handling, hoping to better solve this thorny problem.
1. When the tap breaking department is in the hole, use a tap with a square tap to twist 2 Nuts, and use a steel wire (the number of taps is the same as the number of tap slots) to insert into the empty groove of the tap and nut, and then use a hinge. Pull the square ring to exit the target and pull the broken tap out. If you still can't pull it out, use acetylene flame or torch to anneal the tap, then use the drill to drill. At this time, the diameter of the drill should be smaller than the diameter of the bottom hole, and the hole must be centered to prevent the thread from drilling and the hole should be drilled. Insert a flat or square punch and use a wrench to unscrew the tap.
2. When the broken machine tap is exposed to a workpiece profile of only 2 to 3 mm, a flat steel with a thickness of 2 to 3 mm and a length of 150 to 200 mm is used to drill a hole at a length of 1/2 (the diameter of the hole is tapped. Outside diameter), then flat steel set on broken tap, flat steel and shaft end surface with a gap of 0.5 ~ 1mm. The broken tap and the flat steel are welded to one channel by electric welding. When welding, they should first be welded from the center of the tap and gradually welded to the flat steel. Wait until the broken tap naturally cools, then inject the oil into the flutes of the broken tap, and gently pull the flat steel to loosen the broken tap, so that the tap can be pulled out of the shaft very easily. It is also possible to use a hex nut with a slightly smaller inside diameter than the tap diameter.
3. When the broken tap is exposed to a long working profile, it can be unscrewed with a pair of pliers. In the manufacturing industry, tapping is often encountered on the shaft end, because the large parts of these shaft parts are tempered and tempered, with high toughness and high strength. It is difficult to attack the ribbon and often occurs. Gas tapping phenomenon. In many cases, workpieces are scrapped due to improper handling.
What causes the tap to break during machine tool use?
1. The quality of the machine tap is not good: the main material, CNC tool design, heat treatment, machining accuracy, coating quality, etc. For example, if the size of the tap cross-section transition is too large or the transition fillet is not designed to cause stress concentration, it is easy to break at the stress concentration when used.
The transition of the cross-section at the intersection of the shank and the blade is too close to the weld, resulting in a complex stress stress and superposition of the stress concentration at the cross-section transition, resulting in greater stress concentration, resulting in the tap breaking during use. For example, the heat treatment process is improper. When the tap is heat treated, if the preheating without quenching before quenching, quenching overheating or overheating, not tempering and cleaning prematurely may cause cracks in the tap. To a large extent, this is also an important reason why the overall performance of domestic taps is not as good as that of imported taps.
2. Improper selection of the machine tap: For taps with too high hardness, high-quality machine tools taps should be used, such as cobalt-containing high-speed steel taps, hard alloy taps, and coated taps. In addition, different tap designs are used in different workplaces. For example, the number of flutes, the size, and the angle of the taps of the machine tool have an effect on the chip removal performance.
3. The machine taps do not match with the processed materials: this problem has been paid more and more attention in recent years. In the past, domestic manufacturers always felt that imports were good and expensive, but they were actually suitable. With the increasing number of new materials and the difficulty in processing, in order to meet this need, the variety of tool materials is also increasing. This requires choosing the right tap product before tapping.
4 bottom hole diameter is too small: for example, when processing ferrous metal material M5 × 0.5 thread, with a cutting machine tool tap should use a diameter of 4.5mm drill bit bottom hole, if you use a 4.2mm drill bit to make a bottom hole, when tapping The part of the tap that must be cut must increase, which in turn causes the tap to break. It is recommended to select the correct diameter of the bottom hole according to the type of tap and the material of the tapping material. If the drill bit is not fully qualified, you can choose the largest one.
5 tapping material issues: imperfections, imperfections, local hard points or pores, resulting in an instant loss of balance and break the tap.
6. The machine tool does not meet the accuracy requirement of the tap: The machine tool and the clamping body are also very important, especially for high quality taps, as long as a certain precision of the machine and the clamping body can play a tap performance. Common is not enough concentricity. When the tapping starts, the starting position of the tap is incorrect, that is, the spindle axis is different from the center line of the bottom hole, and the torque is too large during the tapping process, which is the main reason for the tap breaking.
7. The cutting fluid, the quality of lubricants is not good: Many companies in this country have begun to pay attention, many companies that have purchased foreign tools and machine tools have a very profound experience, cutting fluid, lubricant quality problems, processed products Quality is prone to glitches and other adverse conditions, and life will be greatly reduced.
8. Cutting speed and feed rate are unreasonable: When machining problems occur, most users in China reduce the cutting speed and reduce the feed rate. As a result, the tapping force of the tap is reduced, and the threading accuracy of its production is greatly reduced. This increases the roughness of the thread surface, the thread aperture and the thread accuracy are not controlled, and burr and other issues are certainly more inevitable. However, if the feed rate is too fast, too much torque may cause the tap to break. The cutting speed during machine attack is generally 6-15m/min for steel, 5-10m/min for hardened steel or hardened steel, 2-7m/min for stainless steel, and 8-10m/min for cast iron. In the same material, the tap diameter is smaller and the tap diameter is larger.
9. Operators' skills and skills do not meet the requirements: All of the above problems require the operator to make judgments or give feedback to the technicians. However, most of the operators in the country do not pay enough attention. For example, when processing a blind hole thread, when the tap is about to touch the bottom of the hole, the operator does not realize that he still feeds at the tapping speed when not reaching the bottom of the hole, or forcibly breaks the thread when the chip is not flowing smoothly. . It is recommended that operators strengthen their sense of responsibility.
From the above, it can be seen that the cause of the tap fracture can be described as varied. Machine tools, fixtures, workpieces, processes, chucks, and knives are all possible. On paper alone, the real reason may never be found. As a qualified and responsible tool application engineer, the most important thing is to go into the scene, not just imagine. For the simplest example, if the tap cone is too long, the tap will break when hitting the bottom of the bottom hole. If you don't go deep into the field, just guess how the tap performance, the workpiece material, the machining process, etc. are known.
Radial Drilling Machine How to Use Tap Fracture
In the process of using the radial drilling machine, the tap breakage often occurs suddenly under a large force, resulting in the cutting edge of the half tap broken in the screw hole, tightly wedged in the metal, and it is generally difficult to make The cutting edge of the tap is detached from the metal. In order to loosen the tap in the screw hole, a vibration method may be used. When vibrating, use a sharp chisel to reach in the flute's flutes. Use the hammer to gently tap the front and back of the thread to loosen the tap.