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  • jimmy posted an update 1 year, 7 months ago

    Knowledge of Cutting Tools: Drill Technology _ Machining
    Original Title Knowledge of Cutting Tools Drill Technology 1 Craft /Processing 11 Craft According to the diameter and total length of the designed drill bit the alloy bar cutting machine or wire cutting equipment can be selected for fixed-length processing For the bar cut to a fixed length the two ends of the bar are flattened which can be realized on a hand tool grinder Chamfer or punch the ground end face of mining dth bit the alloy bar to prepare for grinding the outer diameter and shank of the drill bit depending on whether the external grinding fixture is a male or female center Expand the full text The excircle diameter of the drill bit the outer diameter of the clearance part and the shank part are processed on a high-precision cylindrical grinder to ensure the design requirements of the outer diameter cylindricity circular runout surface finish and the like In order to improve the machining efficiency on the CNC grinding machine the drill point can be chamfered before the alloy bar is placed on the CNC grinding machine for example the drill point angle of 140 ° can be roughly ground to 142 ° during chamfering After the chamfered alloy bar material is cleaned the chamfered alloy bar material is transferred to a numerical control grinding machine process and each part of the drill bit is processed on a five-axis numerical control grinding machine If it is necessary to improve the finish of the chip groove and excircle of the drill it can also be ground and polished with wool wheel and abrasive before or after the fifth step Of course in this case the drill needs to be processed in more steps For the drill bit that has been processed to be qualified it shall be marked by laser and the content may be the company’s brand LOGO and drill bit specifications and sizes Package the marked drill bit and then deliver it to a professional tool coating company for coating Note 1 Uch as a drill chip groove or spiral shape or straight groove shape This step also includes the negative chamfering of the peripheral cutting edge Then the cutting edge of the drill tip is processed including the tooth clearance part of the drill tip and the relief angle part of the drill point Then the back part of the peripheral cutting edge is processed to grind out a certain amount of drop so as to ensure that the contact surface between the outer diameter part and the hole wall of the workpiece is controlled in a certain proportion 2 Machining of negative chamfering for the cutting edge of drill point

    The grain size of the carbide component (or phase) is typically between 02 and 10 microns and the carbide grains are held together using a metallic binder The bonding metal is generally an iron group metal and cobalt and nickel are commonly used Hence tungsten-cobalt tungsten-nickel and tungsten-titanium-cobalt alloys Tungsten steel drill bit material sintering molding is to press the powder into blank then heat it to a certain temperature (sintering temperature) in the sintering furnace and keep it for a certain time (holding time) and then cool it down so as to obtain the tungsten steel material with the required performance Characteristic And that red hardness of the hard alloy can reach 800-1000 degree The cutting speed of cemented carbide is 4-7 times higher than that of high-speed steel High cutting efficiency Its disadvantages are low bending strength poor impact toughness high brittleness and low ability to withstand impact and vibration 3 Application problem /Measures 31 Worn drill tip Reason 1 The workpiece will move downward under the force of the drill bit The drill bit springs back after drilling through 2 The rigidity of the machine tool is insufficient 3 Bit material is not strong enough 4 Bit runout is too large 5 Insufficient clamping rigidity Drill bit slip Measures 1 Reduce the cutting speed 2 Increase the feed rate 3 Adjust the cooling direction (Internal cooling) 4 Add a chamfer 5 Check and adjust the coaxiality of the drill bit 6 Check whether the relief angle is reasonable 32 Ligament rupture Reason 1 The workpiece will move downward under the force of the drill bit The drill bit springs back after drilling through 2 The rigidity of the machine tool is insufficient 3 Bit material is not strong enough 4 Bit runout is too large 5 Insufficient clamping rigidity Drill bit slip Measures 1 Use a bit with a larger back cone 2 Check the runout range of the main shaft drill bit (<002mm) 3 Punch the top hole with the preset centering drill 4 Use a more rigid bit Hydraulic Chuck with necking sleeve or shrink kit 33
    Accumulate and cut tumor Reason 1 Caused by the chemical reaction between the cutting material and the workpiece material (Mild steel with higher carbon content) Measures 1 Improve the lubricant Increase oil or additive content 2 Increase the cutting speed Reduce the feed rate and contact time 3 If drilling aluminum Drill bits with polished and uncoated surfaces may be used 34 Broken knife Reason 1 The spiral groove of the drill bit is blocked by cutting The cutting is not discharged in time 2 When the hole is almost drilled No reduction in feed rate or change from motorized to manual feed 3 When drilling soft metals such as brass The clearance angle of the drill bit is too large and the rake angle is not ground so that the drill bit is automatically precessed 4 Excessive sharpening of drill edge The phenomenon of chipping occurs and the knife fails to retract quickly Measures 1 Shorten the cycle of changing tools 2 Perfect installation and fixation For example increase the support area increase the clamping force 3 Check the main shaft bearing and sliding groove 4 Use high precision tool holder such as a hydraulic tool holder 5 Use a more ductile material Copyright notice Because some of the articles are from the Internet and some of the articles are pushed without timely contact with the original author If the above copyright issues are involved please contact us to delete or deal with the original author Return to Sohu to see more Responsible Editor