CN110181130B - A kind of cutting tool and processing method for precision machining variable groove width internal thread - Google Patents

Abstract

The invention provides a tool for precisely machining variable-groove-width internal threads, which comprises a cutting blade, a movable slider connected with the cutting blade through a bolt and a base connected with the movable slider through a spring, wherein the cutting blade comprises a blade body part, a main cutting edge positioned at the upper edge of the blade body part and auxiliary cutting edges positioned at the edges of two sides of the blade body part, the main cutting edge and the auxiliary cutting edges are integrally formed with the blade body part, the arc radiuses of the main cutting edge and the auxiliary cutting edges are 0.1mm, and the arc transition radiuses of the auxiliary cutting edges and the blade body part are 0.3 mm. The invention also provides a processing method for precisely processing the variable-groove-width internal thread by using the tool. The invention has the following beneficial effects: the cutting depth can be adjusted by adjusting the displacement of the tool holder end of the machine tool continuously in the process of turning the internal thread, and the rough machining and the finish machining of the internal thread can be completed simultaneously.

Description

A kind of cutting tool and processing method for precision machining variable groove width internal thread

【Technical field】

The invention relates to the technical field of machining, in particular to a tool and a machining method for precision machining of variable groove width internal threads.

【Background technique】

The variable groove width threaded connection of oil pipes or gas pipes not only needs to be tightly and reliably connected, but also needs to have high sealing performance, which puts forward higher requirements for the machining accuracy of variable groove width internal and external threads. At present, turning machining is an effective method for machining threads efficiently. Due to the large length of the oil pipe used for connection, more than 15 meters, and the large diameter of more than 0.5 meters, in the existing processing technology, comb cutters are used for turning processing, but the large-sized oil pipe thread is clamped on the machine tool. Rotation for turning processing leads to changes in the kinematic chain transmission and counterweight ratio of the machine tool, resulting in machining errors. However, since the width of the variable groove width internal thread is gradually reduced, the depth of the thread is gradually reduced. In the turning of internal threads, it is necessary to gradually adjust the depth of cut to meet the processing requirements of variable groove width and depth of internal threads. In the process of adjusting the depth of cut, the cutting force in traditional thread processing is usually large, which increases the number of turnings. The difficulty of precisely adjusting the depth of cut during the threading process results in machining errors.

[Content of the invention]

The invention provides a tool and a machining method for precision machining of variable groove width internal threads, which can effectively improve the machining accuracy and efficiency, and simultaneously complete the rough machining and finishing of the internal threads.

For achieving the above object, the technical scheme of the present invention is:

A tool for precision machining of variable groove width internal threads, comprising a cutting blade, a movable slider connected with the cutting blade through bolts, and a base connected with the movable slider through a spring, the cutting blade includes a blade a main body part, a main cutting edge located on the upper edge of the blade main body part, and a secondary cutting edge located on both side edges of the blade main body part, the main cutting edge and the auxiliary cutting edge are integrally formed with the blade main body part , the circular arc radius of the main cutting edge and the secondary cutting edge is 0.1 mm, and the circular arc transition radius between the secondary cutting edge and the blade body is 0.3 mm.

As an improvement of the present invention, the cutting blade further comprises a groove that is arranged on the blade surface in the shape of a leaf vein, the depth of the groove is 2-3 microns, the bifurcation angle is 15-20°, and the bifurcation is The spacing is 1-2 mm.

As an improvement of the present invention, the end of the groove close to the upper edge of the blade body is 1 mm away from the main cutting edge.

As an improvement of the present invention, the cutting insert includes three bolt holes located in the center of the main body of the insert and arranged in an equilateral triangle, and the bolts are matched with the bolt holes.

As an improvement of the present invention, it further includes a first washer matched with the bolt, the first washer is sandwiched between the bolt and the cutting blade, and the first washer is made of stainless steel production.

As an improvement of the present invention, it further includes a second washer matched with the bolt, the second washer is sandwiched between the cutting blade and the movable slider, the second washer It includes a stainless steel shim layer abutting the cutting blade and having a thermal barrier coating and a rubber sheet abutting the movable slider.

As an improvement of the present invention, it also includes a third gasket disposed between the movable slider and the base, and the third gasket is composited from glass fiber and asbestos.

As an improvement of the present invention, the inner cavity of the base is in the shape of a regular hexagon, the movable slider is in the shape of a regular hexagon, and the movable slider is suspended in the inner cavity by the spring middle.

As an improvement of the present invention, the base is provided with a guide groove at a position corresponding to the third gasket, the third gasket is arranged in the guide groove, and the depth of the guide groove is 5mm.

The present invention also provides a machining method for precision machining of variable groove width internal threads using the tool, comprising the following steps:

Step 1. Add an ultrasonic vibration auxiliary processing device to the original machine tool for turning large-size oil pipe threads;

Step 2: Carry out the cutting force test under the ultrasonic vibration assisted processing condition, using the comb cutter used in actual processing, the cutting depths are 1mm, 3m, 5mm, 7mm, 9mm and 11mm, the cutting speed is 10m/s, and the ultrasonic The vibration frequency is 40000HZ and the amplitude is 15um. The cutting force is collected by a dynamometer to obtain the cutting force of the comb cutter in the direction of the cutting depth under different cutting depths. The abscissa is the cutting depth and the ordinate is the cutting force. The depth of cut cutting force coefficient k _f is obtained by linear fitting;

Step 3: Process the size of the variable groove width thread, and obtain the relationship between the width and depth of the thread. In a given variable groove width thread, according to the design parameters, obtain the minimum width b ₁ , the maximum width b ₂ of the variable groove width thread, and the variable groove width. The minimum depth h ₁ and the maximum depth h ₂ of the thread; the length l ₀ of the variable groove width thread is obtained according to the design parameters of the variable groove width thread, then the distance from the initial end of the thread is the width b(x) and depth h(x) of the thread at x ) are:

The relationship between the width of the thread and the depth of the thread is obtained as follows:

Then, at the same position x, the deterministic relationship between the thread width and depth is obtained, and it does not contain second-order terms, which is linear, that is:

Step 4: Obtain the tool parameters for processing variable groove width threads. The maximum width of the turning tool for processing threads is the relationship between the thread width and depth determined in step 3 of the variable groove width thread, and the relationship between the width of the turning tool and the depth of the blade is obtained. The cutting parameters determined in step 3 can complete the machining of variable groove thread depth at one time;

Step 5: According to the depth of cut cutting force coefficient k _f obtained in step 2 under the ultrasonic vibration assisted machining, the cutting force f ₁ at the cutting end of the turning thread is obtained. According to the relationship between the cutting force and the cutting area, the cutting force coefficient can be The formula for the variation of cutting force during cutting is obtained:

f=k _f b(x)h(x)

Then the cutting force f ₁ at the penetrating end of the trapezoidal thread is:

Cutting force f ₂ at the cut-out end of the trapezoidal thread:

f ₂ =k _f h ₁ b ₁

The minimum depth h ₁ and the maximum depth h ₂ of the variable groove width thread, the displacement difference is:

Δh=h ₂ -h ₁

In the direction of cutting depth, it can meet the adaptive change requirements of cutting depth in thread processing; in the direction of feed speed, it can meet the processing requirements.

The beneficial effects of the present invention are as follows: Considering that ultrasonic vibration-assisted machining can reduce the cutting force under the same conditions, the present invention provides a tool and a machining method for precision machining of variable groove width internal threads, which avoids the need for turning internal threads. Continuously adjust the depth of cut by adjusting the displacement of the tool holder end of the machine tool, and complete the roughing and finishing of the internal thread at the same time.

【Description of drawings】

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, under the premise of no creative work, other drawings can also be obtained from these drawings, wherein:

Figure 1 is a schematic diagram of the connection between the blade, the movable slider and the base;

Figure 2 is a schematic diagram 2 of the connection between the blade, the movable slider and the base;

Fig. 3 is the connection schematic diagram of movable slider, spring and base;

Fig. 4 is the structural representation of cutting insert;

5 is a schematic diagram of a leaf blade-shaped parting groove of a cutting blade;

FIG. 6 is a schematic structural diagram of a variable groove width thread.

【Detailed ways】

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1-3, the present invention provides a tool 100 for precision machining of variable groove width internal threads, comprising a cutting insert 1 and a movable slider connected with the cutting insert 1 by bolts (not shown). 2 and a base 4 connected with the movable slider 2 through a spring, the cutting insert 1 includes a blade body part 11, a main cutting edge 12 located on the upper edge of the blade body part 11 and a main cutting edge 12 located on the blade body part The minor cutting edges 13 on both sides of the edge of 11, the main cutting edge 12 and the minor cutting edge 13 are integrally formed with the insert body 11, and the arcs of the major cutting edge 12 and the minor cutting edge 13 The radius is 0.1 mm, and the arc transition radius of the secondary cutting edge 13 and the insert body portion 11 is 0.3 mm.

4 and 5 again, the cutting blade 1 further includes a groove 14 arranged on the blade surface in the shape of a leaf vein, the depth of the groove 14 is 2-3 microns, and the bifurcation angle θ is 15- 20°, and the bifurcation distance L is 1-2 mm, so as to facilitate the flow and heat dissipation of the cutting fluid in the cutting surface. Specifically, the end of the groove 14 close to the upper edge of the insert body portion 11 is 1 mm away from the main cutting edge 12, because during the cutting process, the length of the chip in contact with the tool 100 is used for internal thread turning Under the parameters, the cutting speed is 0.1m/s-10m/s, the cutting depth is 0-6mm, and the feed rate is 0-2mm/s, the contact length usually does not exceed 1mm. If the distance between the end of the groove and the main cutting edge 12 exceeds 1mm, it is difficult to ensure that the cutting fluid enters the contact between the tool and the workpiece as much as possible under the vacuum adsorption of ultrasonic vibration, so as to reduce the cutting temperature and the friction between the tool and the chip; if it is less than 1mm, the chip will It will come into contact with the groove on the surface of the tool, which will increase the friction between the tool and the chip, make the cutting tool temperature higher, and reduce the tool life and workpiece quality. The cutting edge in the feeding direction at the point of contact with the chip can reduce the contact area between the chip and the tool in the groove 14, and has a chip breaking function, which further reduces the friction between the tool and the chip and reduces the cutting temperature.

The cutting insert 1 includes three bolt holes 15 located in the center of the insert body portion 11 and arranged in an equilateral triangle, and the bolts are matched with the bolt holes 15 .

The tool 100 further includes a first washer (not shown) and a second washer 5 which are matched with the bolt. The first washer is sandwiched between the bolt and the cutting insert 1. The first washer is sandwiched between the bolt and the cutting insert 1. A gasket is made of stainless steel and can be used for preloading. The second gasket 5 is sandwiched between the cutting blade 11 and the movable slider 2 , and the second gasket 5 comprises stainless steel that abuts against the cutting blade 11 and has a thermal insulation coating The gasket layer (not shown) is in contact with the rubber sheet (not shown) of the movable slider 2. The stainless steel gasket layer of thermal insulation coating is used to prevent heat from being transferred to the rubber layer and other components, so as to avoid the Thermal deformation of other materials and softening of rubber materials, the rubber layer is used for vibration isolation, absorbing vibration energy, and reducing vibration during cutting.

The cutter 100 also includes a third gasket 7 disposed between the movable slider 2 and the base 4, the third gasket 7 is made of glass fiber and asbestos, and the glass fiber can contain metal silicon , has a lubricating effect, which is helpful for the movement of the movable slider 2, and the asbestos has the performance of high temperature resistance, so as to avoid the heat in the cutting process causing the third gasket 7 to lose the lubricating effect of its application.

The inner cavity of the base 4 is in the shape of a regular hexagon, and the movable slider 2 is in the shape of a regular hexagon. The sides of the cavity face each other and are spaced in parallel. The movable slider 2 is suspended in the inner cavity by the spring. Referring specifically to FIG. 3 , the springs, along the circumferential direction of the movable slider 2 , clockwise from the 12 o'clock direction, are sequentially provided with a first spring 31 , a sixth spring 36 , a fourth spring 34 , and a first spring 31 . Two springs 32 , a third spring 33 and a fifth spring 35 .

The base 4 is provided with a guide groove 41 at a position corresponding to the third gasket 7 , the third gasket 7 is arranged in the guide groove 41 , and the depth of the guide groove 41 is 5 mm , so as to clamp the third gasket 7 in it.

The present invention also provides a machining method for precision machining of variable groove width internal threads using the tool, comprising the following steps:

Step 1. Add an ultrasonic vibration auxiliary processing device to the original machine tool for turning large-size oil pipe threads;

It should be further noted that the ultrasonic vibration auxiliary processing device includes components such as an ultrasonic power supply, a piezoelectric actuator, an ultrasonic vibration horn, a control system, and the like, wherein the ultrasonic power supply is used to convert industrial power into ultrasonic power. is 40000; the piezoelectric actuator produces repeated motion under the action of the ultrasonic power supply, which stimulates the ultrasonic vibration horn to generate periodic vibration; the ultrasonic vibration horn is used to amplify the vibration generated by the piezoelectric actuator, so that the tool can cut The vibration in the depth direction realizes the periodic contact processing and non-contact processing between the tool and the workpiece, and reduces the cutting force. One end of the ultrasonic vibration horn is connected to the tool holder end of the lathe, and the other end is fixedly connected to the cutting tool. The connection between the ultrasonic vibration horn and the tool holder of the lathe is the vibration node of the ultrasonic vibration horn. Reduce the vibration energy of the ultrasonic vibration horn to dissipate to the tool holder end of the machine tool, and reduce the vibration during processing.

Step 2: Carry out the cutting force test under the ultrasonic vibration assisted processing condition, using the comb cutter used in actual processing, the cutting depths are 1mm, 3m, 5mm, 7mm, 9mm and 11mm, the cutting speed is 10m/s, and the ultrasonic The vibration frequency is 40000HZ and the amplitude is 15um. The cutting force is collected by a dynamometer to obtain the cutting force of the comb cutter in the direction of the cutting depth under different cutting depths. The abscissa is the cutting depth and the ordinate is the cutting force. The depth of cut cutting force coefficient k _f is obtained by linear fitting;

Step 3: Process the size of the variable groove width thread, and obtain the relationship between the width and depth of the thread. In a given variable groove width thread, according to the design parameters, obtain the minimum width b ₁ , the maximum width b ₂ of the variable groove width thread, and the variable groove width. The minimum depth h ₁ and the maximum depth h ₂ of the thread are shown in Fig. 6 , where the design parameters refer to the width, depth, lead of the thread to be processed and its variation at different positions on the tubing. Change curve; in order to ensure the tight and reliable installation of the threaded connection, the thread depth and width of the variable groove width thread change linearly, and with the length (thread distance) of the thread, it is from the initial end of the thread to the end of the thread along the threaded bolt. The distance of the oil pipe, the length l ₀ of the variable groove width thread is obtained according to the design parameters of the variable groove width thread, then the distance from the initial end of the thread is the width b(x) and the depth h(x) of the thread at x are:

According to the above equation, the relationship between the width and depth (length) of the thread is obtained, that is, the relationship between the width of the thread and the depth of the thread is:

Since the depth (length) of the variable groove width internal thread also changes linearly, the determined relationship between the thread width and depth at the same position x is obtained, and it does not contain second-order terms, which is linear, that is:

Step 4: Obtain the tool parameters for processing the variable groove width thread. The maximum width of the turning tool for processing the thread is the relationship between the width and depth of the thread determined in step 3 of the variable groove width thread, and the relationship between the width of the turning tool and the depth of the blade is obtained. The arc radius of the cutting edge is 0.1mm. This is because the depth of the thread changes in the processing of threads with different flute widths. If the transition radius of the cutting edge is small, the transition chip edge will easily chip. It is difficult to meet the smooth transition between the bottom surface and the side surface of the thread. The edge position of the secondary cutting edge 13 and the blade body 11 adopts a circular arc transition with a radius of 0.3mm, mainly considering the transition of this part of the cutter, and does not participate in the cutting process. The larger arc radius is helpful for heat dissipation and cutting fluid during the cutting process. Under the action of the vacuum adsorption effect caused by ultrasonic vibration, it penetrates into the contact between the tool and the workpiece to improve the tool life, and according to the cutting parameters determined in step 3, the processing of the thread depth of the variable groove type is completed at one time, and the roughing and finishing of the thread are realized. Improve the processing efficiency, and the setting of the length of the secondary cutting edge meets the requirements of variable groove width processing with minimum width. The width of the tool and the depth of the thread change;

It needs to be further explained that in the processing of variable groove width threads, traditional tools are used to carry out ultrasonic vibration-assisted turning processing to solve the problem of high-precision thread processing. Under the action of the ultrasonic vibration control system, the tool realizes repeated vibration in the direction of the cutting depth and realizes effective ultrasonic vibration-assisted machining.

Step 5: According to the depth of cut cutting force coefficient k _f obtained in step 2 under the ultrasonic vibration-assisted machining, the cutting force f ₁ at the cutting end of the turning thread is obtained. At this time, since the cutting depth and cutting width are the largest, the cutting force is also the cutting force. When the cutting force is the largest during the process, since the groove width and depth of the thread gradually decrease linearly, the cutting force also gradually decreases linearly; according to the relationship between the cutting force, the cutting area and the cutting force coefficient, the cutting force can be obtained. The formula for changing cutting force during the process:

f=k _f b(x)h(x)

Then the cutting force f ₁ at the penetrating end of the trapezoidal thread is:

Cutting force f ₂ at the cut-out end of the trapezoidal thread:

f ₂ =k _f h ₁ b ₁

The minimum depth h ₁ and the maximum depth h ₂ of the variable groove width thread, the displacement difference is:

Δh=h ₂ -h ₁

In the direction of cutting depth, it can meet the adaptive change requirements of cutting depth in thread processing; in the direction of feed speed, it can meet the processing requirements.

Referring specifically to FIG. 3 , it can be further explained that, in the cutting depth direction Y, the stiffnesses of the second spring 32 , the third spring 33 , the fourth spring 34 , the fifth spring 35 and the sixth spring 36 are set as k ₀ , the pre-compression of the first spring 31, the second spring 32, the third spring 33, the fourth spring 34, the fifth spring 35 and the sixth spring 36 is l ₀ . The changing depth adapts to the processing requirements, and the stiffness k ₁ of the first spring 31 is:

Then in the depth of cut direction Y, it can meet the adaptive change requirements of the depth of cut in thread machining.

In the direction of the feed speed, under the control of the guide groove 41 of the base 4, the movable slider 2 can only move in the direction of the depth of cut Y, and will not move in the direction of the feed speed X, although it moves in the direction of the depth of cut Y, The lengths of the third spring 33, the fourth spring 34, the fifth spring 35 and the sixth spring 36 are changed, but all of them can interact with each other. The resultant force of the six springs 36 in the cutting depth direction Y is 0, which meets the machining requirements.

The beneficial effects of the present invention are as follows: Considering that ultrasonic vibration-assisted machining can reduce the cutting force under the same conditions, the present invention provides a tool and a machining method for precision machining of variable groove width internal threads, which avoids the need for turning internal threads. Continuously adjust the depth of cut by adjusting the displacement of the tool holder end of the machine tool, and complete the roughing and finishing of the internal thread at the same time.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the application listed in the description and the embodiment, and it can be applied to various fields suitable for the present invention. For those skilled in the art, it can be easily Additional modifications are implemented, therefore, the invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the appended claims and the scope of equivalents.

Claims (9)

1. The utility model provides a cutter of internal thread of groove width is become in precision finishing, its characterized in that, including the cutting blade, with the cutting blade pass through bolted connection's portable slider and with portable slider passes through spring coupling's base, the base corresponds portable slider's position is equipped with the direction groove, portable slider can be followed the direction groove removes, the extending direction of direction groove with the cutting blade carries out the cutting depth direction of cutting unanimously, the inner chamber of base is regular hexagon shape, portable slider is regular hexagon shape, every limit of portable slider all with corresponding the limit of the inner chamber of base is just to and parallel interval sets up, portable slider passes through the spring suspension in the inner chamber, follow portable slider's circumference and clockwise from 12 o 'clock directions, the spring includes corresponding each first spring, the first spring that portable slider's limit set up, The second bulletThe stiffness of the spring, the third spring, the fourth spring, the fifth spring, and the sixth spring is set to k in the depth of cut direction₀The stiffness of the first spring is k₁The cutting blade comprises a blade body part, a main cutting edge positioned at the upper edge of the blade body part and auxiliary cutting edges positioned at the edges of two sides of the blade body part, wherein the main cutting edge and the auxiliary cutting edges are integrally formed with the blade body part, the arc radius of the main cutting edge and the arc radius of the auxiliary cutting edge are 0.1mm, and the arc transition radius of the auxiliary cutting edge and the arc radius of the blade body part is 0.3 mm.

2. The tool for precisely machining the variable-groove-width internal thread according to claim 1, wherein the cutting insert further comprises grooves in the shape of leaf veins arranged on the tool face, the depth of the grooves is 2-3 micrometers, the bifurcation angle is 15-20 degrees, and the bifurcation interval is 1-2 millimeters.

3. A tool for precision machining variable slot width internal threads according to claim 2, wherein the end of the recess near the upper edge of the insert body is 1mm from the major cutting edge.

4. The tool of claim 1, wherein the cutting insert includes three bolt holes in a regular triangular arrangement in the center of the insert body, the bolts engaging the bolt holes.

5. The tool for precisely machining a variable-slot-width internal thread according to claim 1, further comprising a first shim engaged with the bolt, the first shim being interposed between the bolt and the cutting insert, the first shim being made of a stainless steel material.

6. The tool for precisely machining the variable-groove-width internal thread according to claim 1 or 5, further comprising a second gasket matched with the bolt, wherein the second gasket is clamped between the cutting blade and the movable sliding block, and comprises a stainless steel gasket layer abutting against the cutting blade and provided with a thermal insulation coating and a rubber sheet abutting against the movable sliding block.

7. The tool for precisely machining the variable-groove-width internal thread according to claim 6, further comprising a third gasket arranged between the movable sliding block and the base, wherein the third gasket is formed by compounding glass fibers and asbestos.

8. The tool for precisely machining the variable-groove-width internal thread according to claim 7, wherein the third gasket is arranged in the guide groove, and the depth of the guide groove is 5 mm.

9. A method for precisely machining a variable-groove-width internal thread by using the tool according to claim 1, comprising the steps of:

step one, adding an ultrasonic vibration auxiliary processing device on an original machine tool for turning large-size oil pipe threads;

step two, carrying out cutting force test under the ultrasonic vibration auxiliary processing condition, utilizing a comb-tooth cutter adopted in actual processing, acquiring cutting force by a dynamometer under the conditions that the cutting depth is 1mm, 3m, 5mm, 7mm, 9mm and 11mm respectively, the cutting speed is 10m/s, the ultrasonic vibration frequency is 40000HZ and the amplitude is 15um, obtaining the cutting force in the cutting depth direction of the comb-tooth cutter under different cutting depths, establishing a graph with the abscissa as the cutting depth and the ordinate as the cutting force, and obtaining a cutting depth and cutting force coefficient k through linear fitting respectively_f；

Step three, processing the size of the variable-groove-width thread to obtain the relationship between the width and the depth of the thread, and obtaining the minimum width b of the variable-groove-width thread in the given variable-groove-width thread according to design parameters₁Maximum width b₂Minimum depth of variable groove width threadDegree h₁Maximum depth h₂(ii) a Obtaining the length l of the variable-groove-width thread according to the design parameters of the variable-groove-width thread₀The width b (x) and depth h (x) of the thread at a distance x from the initial end of the thread are respectively:

obtaining the change relation of the width of the thread along with the depth of the thread as follows:

and then obtaining a definite relation between the thread width and the depth at the same position x, does not contain a second-order term, and is linear, namely:

step four, obtaining the parameters of a cutter for processing the variable-groove-width thread, obtaining the relation between the width of the lathe tool and the depth of the cutting edge by adopting the maximum width of the lathe tool for processing the thread as the relation between the width and the depth of the thread determined in the step three of the variable-groove-width thread, and finishing the processing of the depth of the variable-groove-width thread at one time according to the cutting parameters determined in the step three;

step five, according to the coefficient k of the cutting depth cutting force under the ultrasonic vibration auxiliary processing obtained in the step two_fObtaining the cutting force f at the cutting end of the turned thread₁According to the relationship between the cutting force, the cutting area and the cutting force coefficient, a cutting force variation formula in the cutting process can be obtained:

f＝k_fb(x)h(x)

the cutting of the trapezoidal threadCutting force f at the entry end₁：

Cutting force f of trapezoidal thread cutting end₂：

f₂＝k_fh₁b₁

Minimum depth h of variable groove width thread₁Maximum depth h₂The displacement difference is:

Δh＝h₂-h₁

in the cutting depth direction, the self-adaptive change requirement of the cutting depth in the thread machining can be met; in the direction of the feed speed, the machining requirements are met.

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