What are the methods and precautions for machine tapping?


Due to the problem of low efficiency and unstable quali […]

Due to the problem of low efficiency and unstable quality of hand tapped threads, in actual mass production, machine tapped threads with good quality, high efficiency and low production cost are mainly used. However, in the process of machine tapping, we must also use machines and tools correctly, otherwise it will affect the quality of threaded holes.

(1) The accuracy of the machine tool is the radial runout of the drilling spindle. If the precision of tapping the threaded hole is high, the positioning support surface of the fixture for clamping the workpiece is perpendicular to the drilling spindle center or the tap center, and the threaded bottom hole of the workpiece is perpendicular to the The coaxiality of the tap should generally not be greater than 0.05mm.

(2) Tapping operation mode When the tap is about to tap the thread, the feed should be light and slow to prevent the front end of the tap and the depth of the thread bottom hole of the workpiece from interfering and damaging the tap.

(3) When tapping blind hole threads or deep screw holes, tapping safety chucks should be used to withstand the cutting force. The cutting force of the safety chuck must be adjusted according to the size of the tap to avoid breaking the taper or failing to tap.

(4) In the tapping stroke of the length of the tap cutting part, a uniform and appropriate pressure should be applied to the drill press feed handle to assist the tap to enter the bottom hole, so as to avoid the incomplete thread going down due to the first few taps. When the main shaft is pulled, the thread is scratched. When the calibration part enters the workpiece, the thread is reliably screwed in for tapping, so as to avoid thinning the tooth profile.

(5) When tapping the thread of the through hole, it should be noted that the calibration part of the tap should not be exposed completely, otherwise the tapping phenomenon will occur when the tap is withdrawn from the reverse direction.

(6) Selection of cutting speed The cutting speed of tapping is mainly determined according to the cutting material, tapping oil, tap pitch, thread pitch, and depth of the threaded hole. Generally, the smaller the diameter of the tap is to take the relatively high speed, the larger the diameter of the tap to take the relatively low speed, and the larger the pitch to take the low speed.

(7) When selecting machine tapping threads, the tapping oil is mainly selected according to the material to be processed, and sufficient tapping oil must be maintained to lubricate the tapping parts. In order to ensure the accuracy of the thread, the tapping oil must conform to the process Requirements, can not use rapeseed oil, machine oil, regenerated oil and other oils instead.

The above are the common problems and precautions of the thread tapping processing technology. Strictly operating in accordance with the rules and regulations when using the tapping machine can effectively avoid the occurrence of failures. When selecting raw materials, using products that meet the relevant standards can improve the quality of the workpiece.

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