CN114769750B

CN114769750B - Spiral fluted tap for machining small-diameter large-pitch blind hole and use method

Info

Publication number: CN114769750B
Application number: CN202210587077.8A
Authority: CN
Inventors: 王晟; 马鹏飞; 杨志嘉
Original assignee: Tianjin Hongsheng Technology Co ltd
Current assignee: Tianjin Hongsheng Technology Co ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2024-07-26
Anticipated expiration: 2042-05-27
Also published as: CN114769750A

Abstract

The invention relates to a spiral fluted tap for processing a small-diameter large-pitch blind hole, which comprises a plurality of taps used in sequence, wherein the large diameter of each tap from a first tap to a last tap is equal to the sum of the large diameter and the cutting thickness of the previous tap. According to the invention, each spiral fluted tap sequentially cuts under the condition of designed cutting quantity, and the external force born by each spiral fluted tap is in a safe range, so that the problem of easy breakage during processing of a single tap is solved. By utilizing the characteristic that the screwing teeth have no back angle, the spiral fluted tap is only screwed into a hole processed by the last spiral fluted tap rapidly, and the first few teeth with back angles are prevented from being clamped at the hole and causing the breakage of the current tap. Through the combination of a plurality of spiral fluted taps and structural improvement, the machining efficiency is greatly improved, the fracture problem is solved, and under the comprehensive effect, the production cost is greatly reduced, and the production efficiency is greatly improved.

Description

Spiral fluted tap for machining small-diameter large-pitch blind hole and use method

Technical Field

The invention belongs to the technical field of screw tap structure improvement, and particularly relates to a spiral groove screw tap for machining a small-diameter large-pitch blind hole and a use method thereof.

Background

The screw hole is the structure that often runs into in the machining field, and it generally adopts the screw tap to process, and the screw hole generally adopts straight flute tap when being the through-hole, and the screw hole generally adopts the spiral flute tap when being the blind hole, and wherein the spiral flute tap of chip removal need be adopted in the blind hole screw machining, and the spiral direction of spiral flute is the same with the direction that the screw tap rotated the cutting, and the right-hand member of so-called, the piece that cuts upwards discharges along the spiral flute. In the threaded bore is a blind hole of high pitch, which belongs to non-standard components, such as: when the blind hole is machined, the screw tap is stressed greatly when in cutting due to the fact that the screw pitch is large, the problem of sudden fracture during the machining of the screw tap often occurs, most manufacturers adopt lathes to machine, and the cutter is used for gradually cutting the threaded hole, but the machining method is very low in efficiency, and the production and manufacturing cost is greatly increased.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a spiral fluted tap for processing a small-diameter large-pitch blind hole. In the screw tap, the processing efficiency is greatly improved through the combination of a plurality of spiral groove screw taps and the structural improvement, the problem of fracture is solved, the production cost is greatly reduced, and the production efficiency is greatly improved under the comprehensive effect.

The technical scheme adopted by the invention is as follows:

The utility model provides a spiral fluted tap is used in processing of minor diameter large pitch blind hole which characterized in that: the large diameter of each tap from the first tap to the last tap is equal to the sum of the large diameter of the previous tap and the cutting thickness;

the first screw tap comprises a cutting tooth section and an expanding tooth section from the lower end to the upper end, and the cutting tooth section is provided with a plurality of cutting teeth at intervals according to screw pitch of a screw hole; the diameter-enlarging teeth segments are provided with a plurality of diameter-enlarging teeth at intervals according to screw pitch of the screw holes;

each tap behind the first tap comprises a screwing tooth section and an expanding tooth section from the lower end to the upper end, and the screwing tooth section is used for quickly screwing each tap behind into a hole machined by the previous tap; the structure of the screwing teeth in each screwing tooth section is the same as that of the diameter-expanding teeth of the diameter-expanding tooth section of the previous tap;

The cutting cone angle of the cutting tooth segment is smaller than 10 degrees;

The cutting cone angle of the first screwing tooth of the screwing tooth section is 20-40 degrees, and the screwing tooth has no back angle.

Further: the number of the cutting teeth is 3-5.

Further: 2 teeth are screwed.

Further: the rake angle of each cutting tooth is 1-6 degrees.

Further: the relief angle of each cutting tooth is 4-5 degrees.

Further: the relief angle of each expanding tooth is 1-2 degrees.

Further: the number of the taps is 4-8.

Further: the helix angle of the spiral groove is 10-15 degrees.

The invention further provides a use method of the spiral fluted tap for processing the small-diameter large-pitch blind hole, which comprises the following steps:

Selecting the number and the structure of taps;

Performing first machining by using a first tap, and cutting a shallow groove of the threaded hole;

and (3) cutting and expanding the shallow slot of the last threaded hole by using the second tap, and continuing to use the next tap until the last tap is used for cutting and expanding the finished threaded hole.

The invention has the advantages and positive effects that:

According to the invention, a plurality of spiral groove taps with average increased diameters are selected, the large diameter of each spiral groove tap is equal to the sum of the large diameter and the cutting thickness of the last spiral groove tap, so that each spiral groove tap sequentially cuts under the condition of designed cutting quantity, the external force born by each spiral groove tap is in a safe range, and the problem that a single tap is extremely easy to break during processing is solved. Besides the first screw tap is used for cutting shallow grooves of the threaded hole, other screw tap holes are sequentially cut and expanded, two screwing teeth are designed at the lower end of each screw tap hole, and the screw tap is quickly screwed into a hole machined by the last screw tap by utilizing the characteristic that the screwing teeth have no relief angle, so that the first few teeth with relief angles are prevented from being clamped at the hole and causing the breakage of the current screw tap. Through the combination of a plurality of spiral fluted taps and structural improvement, the machining efficiency is greatly improved, the fracture problem is solved, and under the comprehensive effect, the production cost is greatly reduced, and the production efficiency is greatly improved.

Drawings

FIG. 1 is a schematic view of the construction of a first spiral fluted tap of the present invention;

FIG. 2 is a schematic view of the construction of a second spiral fluted tap of the present invention;

FIG. 3 is a schematic view of the construction of a third spiral fluted tap of the present invention;

FIG. 4 is a schematic view of the construction of a fourth spiral fluted tap of the present invention;

FIG. 5 is a view of the first spiral fluted tap in operation;

Fig. 6 is a view showing the operation of the second spiral fluted tap.

Detailed Description

The invention will now be further illustrated by reference to the following examples, which are intended to be illustrative, not limiting, and are not intended to limit the scope of the invention.

The invention discloses a spiral fluted tap for processing a small-diameter large-pitch blind hole, wherein a tap head 2 is arranged at the lower end of a threaded shank 1, and the innovation of the invention is that: including multiple taps used in sequence, the major diameter of each of the first tap to the last tap is equal to the sum of the major diameter and the cutting thickness of the previous tap.

The first screw tap comprises a cutting tooth section A and an expanding tooth section B from the lower end to the upper end, and the cutting tooth section is provided with a plurality of cutting teeth 4 at intervals according to screw pitch of a screw hole; the expanding tooth segments are provided with a plurality of expanding teeth 3 at intervals according to screw pitch of the screw holes.

Each tap behind the first tap comprises a screwing tooth section D and an expanding tooth section B from the lower end to the upper end, and the screwing tooth section is used for quickly screwing each tap behind into a hole 9 machined by the previous tap; the structure of the screwing teeth in each screwing tooth section is the same as that of the expanding teeth of the expanding tooth section of the previous tap.

The cutting cone angle alpha of the cutting tooth segment is less than 10 degrees. The number of the cutting teeth is 3-5. 2 teeth are screwed. The rake angle of each cutting tooth is 1-6 degrees. The relief angle of each cutting tooth is 4-5 degrees. The relief angle of each expanding tooth is 1-2 degrees. The number of the taps is 4-8. The helix angle of the spiral groove is 10-15 degrees. The cutting cone angle beta of the first screwing tooth of the screwing tooth section is 20-40 degrees, and the screwing tooth has no back angle.

As shown in fig. 1-6, the diameter of the threaded hole to be machined is 16 mm, the pitch is l=8 mm, and the effective depth of the thread is 36 mm; the bottom hole diameter is 12 mm and the bottom hole depth is 52 mm.

According to the parameters of the composition, the hardness and the like of the material of the threaded hole, four screw taps are selected, and each screw tap is provided with four spiral grooves.

Total volume required to be cut for a threaded bore = cutting volume per turn of teeth x number of turns

Cutting volume of each ring of teeth = trapezoid tooth cross-sectional area x perimeter of threaded hole

Number of turns = effective depth/(pitch)

The cross-sectional dimensions of the trapezoidal teeth given by the customer are: the upper bottom is 2 mm, the lower bottom is 4 mm, and the tooth height is 2 mm.

The method comprises the following steps of:

number of turns = 36 +.8 = 4.5

Cutting volume per turn of teeth= ((2+4) ×4/2) × (16×3.14) = 602.88

Total volume of screw holes to be cut = 602.88 x 4.5 = 2712.96

4 Taps are selected, the cutting thickness of each tap is 1 millimeter, the major diameter D1 of the first tap I is 13 millimeters, the major diameter D2 of the second tap II is 14 millimeters, the major diameter D3 of the third tap III is 15 millimeters, and the major diameter D4 of the fourth tap IV is 16 millimeters.

Generally, the greater the depth of the hole, the smaller the helix angle of the helical groove, as in the hole configuration of the figure, the helix angle of the helical groove is 13.5 degrees.

The total volume of the first tap cut was calculated as 40% of the total volume = 2712.96 x 0.4 = 1085.184

Cutting volume per turn of teeth of the first tap = 1085.184 +.4.5 = 241.152

Cross-sectional area of trapezoidal teeth of tap = 241.152 +.13 = 18.55, the height of trapezoidal teeth is 2 millimeters, then the sum of trapezoidal teeth upper base and lower base = 18.55 x 2 +.4 = 9.28, according to upper base: the ratio of bottom = 1:2 designs the dimensions of the upper and lower bottom of the tap trapezoidal teeth.

The cutting volume of the second tap is 30% of the total volume, the cutting volume of the third tap is 20% of the total volume, the cutting volume of the fourth tap is 10% of the total volume, and the sizes of the upper bottom and the lower bottom of the trapezoidal teeth are respectively designed according to the calculation process.

The width of the land is calculated as major diameter x 3.14 ≡4 ≡2.6, the major diameter is the major diameter of each tap, 3.14 is the circumference ratio, 4 is the number of spiral grooves, and 2.6 is the calculation constant.

The process of calculating the cutting cone angle of the first tap is as follows:

Cutting cone angle = arctan ((major tap diameter-bottom hole diameter)/(2 > (number of cutting teeth x pitch))

In the cutting segment a of the first tap of fig. 1, there are 5 cutting teeth 4, the tap major diameter is 13, the bottom hole diameter is 12, the pitch is 8, and the cutting cone angle α=arctan ((13-12)/(2/(5×8))=0.72 degrees. (in the figure, the cutting cone angle is appropriately enlarged in drawing so that the cutting cone angle can be seen)

The rake angle of each cutting tooth is 1-6 degrees. The relief angle of each cutting tooth is 4-5 degrees, preferably 4.5 degrees.

The enlarged tooth segment B of the first tap had 2 enlarged teeth 3 with a major diameter of 13 mm, which corrected the shallow grooves of the threaded hole cut by the cutting tooth segment. The diameter-enlarging tooth is a complete tooth form (complete tooth form means tooth height of 2mm, length of upper bottom and lower bottom and ratio of upper bottom and lower bottom are in accordance with the ratio of upper bottom and lower bottom mentioned in the above calculation process), but it has a certain relief angle, preferably 1 degree.

As shown in fig. 2, the lower-end screwing tooth segment D of the second tap has 2 screwing teeth, the structure of the 2 screwing teeth is the same as that of the diameter-enlarging tooth 3 of the diameter-enlarging tooth segment of fig. 1, and the first screwing tooth at the lowest end has a cutting cone angle beta of 30 degrees as shown in the figure. Because the back angle of the 2 screwing teeth is zero, the back angle is not existed, and the first screwing teeth 6 have a cutting cone angle of 30 degrees, the screw can be quickly screwed in like the screwing state of a bolt when the screwing teeth enter the hole processed by the first screw tap, the cutting process is avoided, and the plurality of diameter expanding teeth at the upper end are convenient for carrying out subsequent cutting and diameter expanding.

The tap head at the upper end of the screwing tooth section of the second tap is provided with 5 diameter-enlarging teeth, and as can be seen from the figure, the bottom diameter of the diameter-enlarging tooth section above the broken line is enlarged according to the size of the large diameter, so that the large diameter of the trapezoid tooth with the same tooth height is equal to 14mm, each diameter-enlarging tooth is in a complete tooth shape, but has a back angle of 1 degree, and the cutting and diameter-enlarging process is completed through the cutting of the back angle.

The screwing teeth at the lower end of the third tap are in the structure of second tap expanding teeth 5, the first screwing teeth at the lower end also have a cutting cone angle beta of 30 degrees, the screwing teeth of the fourth tap also have the structure of third tap expanding teeth 7, and the lower end also has a cutting cone angle. The diameter-enlarging teeth 8 of the fourth screw tap are all the sizes of finished threads, and the finished threaded holes are obtained after the diameter-enlarging teeth cut and enlarge.

The use process of the four taps with the structure is as shown in fig. 5 and 6: (FIGS. 5 and 6 are only intended to illustrate the general operation of different taps, the inner walls of the bore are not drawn in full, including but not limited to shallow grooves in the bore)

Selecting 4 taps and the structure of each tap according to the calculation process;

As shown in fig. 5, a first tap is used for first machining, a plurality of cutting teeth 4 sequentially cut on the inner wall of a bottom hole 11, a hole wall 9 is continuously cut, and after the cutting is finished, the last two diameter expanding teeth finish cutting and diameter expanding of the machining, and a shallow groove of a threaded hole is obtained;

As shown in fig. 6, the first tap is withdrawn, the second tap is replaced, and the screwing teeth enter the hole machined by the first tap, and the screwing teeth are screwed into the hole rapidly by the screwing teeth because the hole wall is provided with a shallow groove of the threaded hole and no back angle is equivalent to screwing the head of the bolt. The diameter-enlarging teeth 5 at the upper ends of the screwing teeth continue to enter the holes, and the middle diameter of the diameter-enlarging teeth is enlarged (large diameter is enlarged) due to the rear angle of the diameter-enlarging teeth, so that the diameter-enlarging teeth continue to cut and enlarge the shallow grooves of the threaded holes of the hole walls.

And then continuously replacing the third tap and the fourth tap, and obtaining a threaded hole of a finished product after the diameter expansion tooth section of the fourth tap is cut and expanded.

By comparison, the ratio of the number of processes performed by a conventional lathe to the number of processes performed at the same time of the present invention is 1:10.

Claims

1. The utility model provides a spiral fluted tap is used in processing of minor diameter large pitch blind hole which characterized in that: the large diameter of each tap from the first tap to the last tap is equal to the sum of the large diameter of the previous tap and the cutting thickness;

The cutting cone angle of the cutting tooth segment is smaller than 10 degrees;

the cutting cone angle of the first screwing tooth of the screwing tooth section is 20-40 degrees, and the screwing tooth has no back angle;

3-5 cutting teeth;

2 screwing teeth;

The front angle of each cutting tooth is 1-6 degrees;

The rear angle of each cutting tooth is 4-5 degrees;

the relief angle of each expanding tooth is 1-2 degrees.

2. The spiral fluted tap for small diameter, high pitch blind hole machining according to claim 1, wherein: the number of the taps is 4-8.

3. The spiral fluted tap for small diameter, high pitch blind hole machining according to claim 2, wherein: the helix angle of the spiral groove is 10-15 degrees.

4. The method of using the spiral fluted tap for processing the small-diameter large-pitch blind hole according to claim 3, wherein: the method comprises the following steps:

Selecting the number and the structure of taps;