A spiral flute tap and its processing method

Abstract

The present invention discloses a spiral flute tap and a processing method thereof, including: a cutting part and a clamping part; the front part of the cutting part is a cutting cone, and the rear part is a calibration part; the cutting part has a cutting edge band and a groove, the cutting edge band and the groove are spirally and alternately distributed, the cutting edge band has a thread cutting edge, and the actual thread helix angle ω2 machined on the cutting edge band is greater than the helix angle ω1 of the groove; the processing method includes the steps: Step 1, blanking; Step 2, matrix forming; Step 3, groove machining; Step 4, cutting part thread machining; Step 5, cutting cone machining. The machined spiral flute tap cuts more smoothly during the tapping process, eliminates the undercut phenomenon that occurs in the threads machined by ordinary spiral flute taps, and improves the service life of the spiral flute tap.

Description

Technical Field

[0001] The present invention relates to the technical field of cutting tools, and particularly relates to a spiral flute tap and a processing method thereof. Background Art

[0002] During the tapping process, the tap will be subjected to a reaction force from the workpiece being processed. For an ordinary spiral flute tap, since the spiral angle is to the right, the reaction force is perpendicular to the spiral angle and towards the lower right direction, and one of the component forces is perpendicular to the axis and downward. Due to this component force, the tap is subjected to a downward pulling force during processing, and this pulling force often causes overcutting in the processed hole and the expansion of the hole diameter. Summary of the Invention

[0003] The present invention aims to provide a spiral flute tap and a processing method thereof, so that the spiral flute tap processed is more stable during thread tapping, and the overcutting phenomenon occurring in the threads processed by an ordinary spiral flute tap is eliminated.

[0004] To achieve the above object, the present invention provides a spiral flute tap, which is characterized in that it includes: a cutting part and a clamping part; the front part of the cutting part is a cutting cone, and the rear part is a calibration part; the cutting part has a cutting edge band and a groove, the cutting edge band and the groove are spirally and alternately distributed, there is a thread cutting edge on the cutting edge band, and the thread spiral angle ω2 of the cutting edge band is greater than the spiral angle ω1 of the groove.

[0005] Preferably, the thread spiral angle ω2 of the cutting edge band is 2 - 5° larger than the spiral angle ω1 of the groove.

[0006] Furthermore, the processing method includes the steps of:

[0007] Step 1: Cut the material, process the base body, and perform pre-treatment;

[0008] Step 2: Shape the base body, process the base body to form the cutting part and the clamping part, and machine the square tail of the clamping part;

[0009] Step 3: Machine the groove, machine a spiral tap groove on a grinding machine, the spiral angle of the groove is ω1, and calculate the lead by the lead formula Calculate the lead;

[0010] Step 4: Machine the thread of the cutting part, set the spiral angle ω2 of the tap cutting edge band to be 2 - 5° larger than the spiral angle ω1 of the groove, and the lead T' required for grinding the thread can be calculated by the lead formula Input the value of the lead T' into the grinding machine program, and then adjust the machine tool state, so that the thread spiral angle ω2 of the ground cutting edge band is larger than the spiral angle ω1 of the groove.

[0011] Step 5: Machine the cutting cone of the cutting edge. After machining the thread of the cutting edge, grind the cutting cone of the cutting edge.

[0012] Compared with the existing technology, the present invention has the following beneficial effects:

[0013] 1. Improve the stability of the spiral flute tap during thread tapping;

[0014] 2. Eliminate the overcut phenomenon that often occurs in ordinary spiral flute taps;

[0015] 3. Improve the service life of the spiral flute tap. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of the present invention;

[0017] Figure 2 is a schematic structural diagram of an ordinary spiral flute tap;

[0018] Figure 3 is Figure 1 a schematic diagram of the tooth profile of a single tooth of the present invention after grinding the thread in the P-P direction;

[0019] Figure 4 is Figure 2 a schematic diagram of the tooth profile of a single tooth of an ordinary one after grinding the thread in the P'-P' direction;

[0020] In the figure: 1 - cutting edge, 101 - cutting edge band, 102 - groove, 2 - clamping portion, 3 - cutting cone. DETAILED DESCRIPTION OF THE INVENTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] A spiral flute tap of the present invention is characterized in that it includes: a cutting edge 1 and a clamping portion 2; the front part of the cutting edge 1 is a cutting cone 3, and the rear part is a correction portion; the cutting edge 1 has a cutting edge band 101 and a groove 102, the cutting edge band 101 and the groove 102 are spirally and alternately distributed at intervals, the cutting edge band 101 has a thread cutting edge, and the thread helix angle ω2 of the cutting edge band 101 is greater than the helix angle ω1 of the groove 102.

[0023] Preferably, the thread helix angle ω2 of the cutting edge band 101 is 2 - 5° larger than the helix angle ω1 of the groove 102.

[0024] Furthermore, the processing method includes the steps:

[0025] Step 1: Cut the material, machine the substrate, and perform pretreatment;

[0026] Step 2, Matrix forming: Process the matrix to form the cutting edge 1 and the clamping part 2, and machine the square tail of the clamping part 2.

[0027] Step 3, Groove machining: Machine a spiral tap groove 102 on a grinding machine. The spiral angle of the groove 102 is ω1, and the lead is calculated by the lead formula to calculate the lead.

[0028] Step 4, Cutting edge thread machining: Set the spiral angle ω2 of the tap cutting edge band 101 to be 2 - 5° larger than the spiral angle ω1 of the groove 102. The lead T' required for grinding the thread can be calculated by the lead formula Input the value of the lead T' into the grinding machine program, and then adjust the machine state. Then the spiral angle ω2 of the ground cutting edge band 101 can be made larger than the spiral angle ω1 of the groove 102.

[0029] Step 5, Cutting edge taper machining: After machining the cutting edge thread, grind the cutting edge taper 3.

[0030] Usually, a tap back angle will be ground when grinding the tap thread. As shown in Figure 4 , the grinding wheel gradually descends from point A to point B to form the back angle. That is, point A is the starting point of the front tool face cutting. Taking the outer circle as an example for illustration, the grinding shapes of other parts are the same. AC is the outer circle position before grinding, and AB is the outer circle position after grinding. The grinding descent amount is K.

[0031] When the spiral angle ω2 of the ground tap thread is larger than the spiral angle ω1 of the groove 102, that is, when grinding is carried out according to the present invention, during the grinding process of the grinding wheel from the cutting edge 1 end face to the clamping part 2 direction, the starting point of the formed descent amount will gradually move backward, that is, gradually move from the MN position in Figure 1 to the MN' direction; looking at a single cutting tooth alone, as shown in Figure 3 , the starting point of the cutting tooth descent amount gradually moves from A to A', the descent amount is K', and there is no descent amount in the AA' section. The descent amount K' is generated from point A' to point B.

[0032] When tapping with the spiral groove tap made by the present invention, since the ω2 of the ground thread becomes larger, the starting point of forming the back angle moves backward, and the backward movement amount is larger closer to the shank. As a result, the corrected teeth become "less sharp", and the closer to the shank, the "less sharp" they are. This less sharp cutting edge causes an upward "resistance" to the tap during tapping. This force can balance the downward pulling force received by the spiral groove tap during tapping, thereby ensuring smooth cutting of the tap, smooth chip evacuation, eliminating the overcut phenomenon of the tap, and at the same time improving the edge strength of the corrected teeth of the tap, thus improving the service life of the spiral groove tap.

[0033] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention. However, these corresponding changes and modifications should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A processing method for a spiral fluted tap, characterized in that The spiral flute tap comprises: a cutting part (1) and a clamping part (2); the front part of the cutting part (1) is a cutting cone (3), and the rear part is a calibration part; the cutting part (1) has a cutting edge band (101) and a groove (102), the cutting edge band (101) and the groove (102) are spirally and alternately distributed, the cutting edge band (101) has a thread cutting edge, and the thread helix angle on the cutting edge band (101) ω 2 is greater than the helix angle of the groove (102) ω 1; the thread helix angle on the cutting edge band (101) ω 2 is larger than the helix angle of the groove (102) by ω 1 by 2 to 5°. The processing method includes the steps of: Step 1, blanking, processing the base body, and performing pre-treatment; Step 2, forming the base body, processing the base body to form the cutting edge (1) and the clamping part (2), and machining the square tail of the clamping part (2); Step 3, machining the groove. A spiral tap groove (102) is machined on a grinding machine, and the spiral angle of the groove (102) is ω 1. Calculate the lead by the lead formula T = where D is the diameter of the substrate; Step 4: Machine the thread of the cutting edge, and set the thread helix angle of the cutting edge land (101) of the tap ω 2 larger than the helix angle of the groove (102) ω by 2 to 5°, and from the lead formula T' = the required lead T' for thread grinding can be calculated, where D is the diameter of the substrate. Input the value of the lead T' into the grinding machine program, and then adjust the machine tool state, so that the thread helix angle of the ground cutting edge land (101) ω is 2 larger than the helix angle of the groove (102); ω during the grinding process of the grinding wheel from the end face of the cutting edge (1) towards the clamping part (2), the starting point of the amount of descent will gradually move backward; Step 5, machining the cutting cone of the cutting edge. After machining the thread of the cutting edge, grind the cutting cone (3) of the cutting edge.

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