CN116673505A - An oil-gas boring bar mechanical spindle structure and its working method - Google Patents

Abstract

The invention discloses an oil-gas boring bar mechanical main shaft structure and a working method thereof. The method comprises the following steps: the front end of the cylindrical roller bearing is provided with a double-row cylindrical bearing as a positioning bearing, and the rear end of the cylindrical roller bearing is provided with a double-row cylindrical bearing as a floating bearing; the boring bar is connected with the main shaft through a flat key, and is restrained from moving along the circumferential direction between the boring bar and the main shaft, and moves axially under the action of the propelling structure; after the compressed air and the ice oil are mixed in the oil-gas mixer, the compressed air and the ice oil are connected into the internal passage of the main shaft, the bearing is lubricated, the cooling is carried out, and the oil-gas is discharged from the labyrinth ring structure to take away heat. The invention can realize high-rotation-speed continuous cutting of the spindle and spindle extension processing of the W-axis boring bar simultaneously, and improves the sensitivity and timeliness of temperature control.

Description

An oil-gas boring bar mechanical spindle structure and its working method

technical field

The invention relates to the technical field of boring bar mechanical spindles, in particular to an oil-gas boring bar mechanical spindle structure and a working method thereof.

Background technique

In the field of machining, boring bars are a common process for machining inner holes or grooves. The traditional mechanical spindle structure has some technical problems when processing boring bars, such as the bearing heating problem and the spindle thermal extension problem. When running at high speed and for a long time, the mechanical spindle is prone to generate too much heat, which will cause the temperature of the bearing to rise and the thermal extension of the spindle, which will affect the processing quality and precision.

The traditional mechanical spindle structure often cannot meet the requirements of high-speed continuous cutting, nor can it realize the extension processing of W-axis boring bar spindle. The existing cooling method mainly uses cooling oil to circulate oil to cool down the peripheral water jacket of the heat generating part. However, this indirect cooling method has some disadvantages, such as insensitive temperature control, large delay, and the parts are always in the environment of alternating cold and hot, resulting in shortened service life, and because it cannot meet the needs of high-speed continuous cutting, the versatility Low, not suitable for processing in industries such as abrasive tools.

Contents of the invention

The purpose of the present invention is to provide an oil-air boring bar mechanical spindle structure and its working method, which can simultaneously realize the high-speed continuous cutting of the spindle and the extension processing of the W-axis boring bar spindle, and at the same time directly cool down the heat-generating parts of the spindle to improve the temperature control. Sensitivity and timeliness, thereby increasing the service life of parts and enhancing their versatility.

The technical solution to realize the object of the present invention is: a mechanical spindle structure of an oil-gas boring bar, including a spindle outer cover, a spindle mandrel, a boring bar, a support bearing, a bearing gland, a dust-proof mechanical labyrinth, a metal cutting tool, a broach mechanism, Hollow internal cooling module, oil-air cooling and control device, temperature detection device, speed detection device, of which:

Spindle jacket, fit into the center hole of the machine tool spindle box body with a gap, and connect to the end face;

The main shaft mandrel is arranged inside the main shaft outer cover, and is a rotary part, and the main shaft mandrel is provided with a flat key;

The boring bar is arranged inside the main shaft mandrel, connected with the slot inside the main shaft mandrel, rotates together with the main shaft mandrel, and can be axially displaced;

Support bearings are arranged between the main shaft outer casing and the main shaft mandrel to provide slewing support;

The bearing gland is arranged at the end of the bearing to fix the position of the bearing, and adjust the thickness of the bearing gland to adjust the pretightening force of the supporting bearing, so as to produce different spindle cutting performance;

The dust-proof mechanical labyrinth is arranged between the support bearing and the bearing gland to prevent impurities such as cutting particles and coolant from contaminating the bearing;

Metal cutting tools are set on the end face of the boring bar to cut metal materials;

a broaching mechanism, arranged inside the boring bar, for tensioning the metal cutting tool;

A hollow internal cooling module, placed in the center of the rod of the broach mechanism, to cool the pair of metal cutting tools;

The oil-air cooling and control device is placed outside the main shaft. The oil-air cooling medium passes through the pipeline and the flow channel preset in the main shaft jacket, and the medium enters the inside of the bearing to cool the high-speed bearing;

Temperature detection device for real-time detection of spindle bearing temperature;

The speed detection device is used to detect the real-time rotation speed of the spindle.

Further, double-row cylindrical roller bearings are used for radial support of the front end and the rear end.

Furthermore, the front end adopts the O-shaped support of the oblique support bearing and the double-row cylindrical roller bearing for positioning support; the rear end adopts the double-row cylindrical roller bearing for floating support; the bearing temperature rises, and the rigid material of the main shaft extends to the rear end .

Further, the oil-gas cooling and control device is as follows:

The compressed air generated by the air compressor and the ice oil cooled by the oil cooling equipment are passed into the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the internal design passage of the spindle and flows into the bearing position for bearing lubrication and cooling. , the oil and gas are discharged from the labyrinth structure to take away the heat.

Furthermore, the boring bar is connected to the main shaft through a sliding flat key, and the circumferential movement of the main shaft and the boring bar is constrained, and the axial movement can be carried out axially under the drive of the feed screw and the motor.

Further, the temperature sensor detects the temperature rise state of the main shaft bearing position in real time, and sets the temperature rise interval. If it is higher than the interval value, the supply rate of the oil-air cooling medium is increased to lower the temperature. When the temperature is lower than the interval value, the supply rate of the oil-air cooling medium is reduced. , to stabilize the temperature within the set range.

Further, it specifically includes a boring bar, a main shaft, a front gland of a front bearing, a front labyrinth ring, a cylindrical roller bearing, an oil-gas splitter ring, an angular contact bearing, a rear gland of a front bearing, a rear labyrinth ring, a lock nut, and a tee Joints, rear bearing outer ring supports, rear cylindrical roller bearings, rear bearing glands, claws, pull rods, shrapnel, shrapnel glands, oil-air mixers, air compressors, oil cooling equipment, flat keys, spindle housings, tools .

Furthermore, the boring bar is connected to the main shaft through 4 flat keys to constrain the circular movement, and the boring bar moves axially together with the claws, pull rods, shrapnel, shrapnel gland, and tool, and realizes the tool extension processing function through the feed movement ;Under the preset force of the shrapnel, the claw stretches backwards to tighten the tool;

There are 3 bearings at the front end of the main shaft: 1 cylindrical roller bearing and 2 angular contact bearings; the outer ring of the bearing is fixed through the front gland of the front bearing and the rear gland of the front bearing, and the preload of the front bearing is achieved by locking the lock nut ; The rear bearing is a rear cylindrical roller bearing, which is installed on the main shaft and the support of the outer ring of the rear bearing to provide radial support, and the rear bearing gland locks the bearing to prevent axial movement.

Further, the compressed air generated by the air compressor is mixed with the ice oil cooled by the oil cooling equipment into the oil-air mixer, and the flow is divided through the three-way joint, and connected to the internal design passage of the main shaft through the main shaft shell and the rear bearing outer ring support , to cool down, and the oil and gas are discharged from the front labyrinth ring and the rear labyrinth ring.

A working method of the mechanical spindle structure of the oil-gas boring bar as described, specifically as follows:

Equipped with cylindrical roller bearings with oil-air boring bar mechanical spindle structure, the front end adopts double-row cylindrical bearings, and 2 large steel ball angular contact spindle bearings are used as positioning bearings for axial and radial support, and the rear end adopts double-row cylindrical bearings as positioning bearings. floating bearing;

Boring bar expansion and contraction: The boring bar is connected to the main shaft through a flat key, restricting the circular movement between the main shaft and the main shaft, and rotating together with the main shaft, and the axial direction moves axially under the action of the propulsion structure. After the metal cutting tool is extended, the internal control process of the box is carried out processing;

Cooling control: The compressed air generated by the air compressor and the ice oil cooled by the oil cooling equipment are mixed with the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the internal passage of the main shaft and flows into the bearing position for bearing lubrication and cooling. Cooling down, the oil and gas are discharged from the labyrinth ring structure to take away the heat.

Compared with the prior art, the present invention has the remarkable advantages of:

(1) Reduce the heating of the bearing, reduce the thermal extension of the spindle, and improve the precision of the spindle;

(2) At the same time, high-speed continuous cutting and W-axis boring bar spindle extension processing are realized, the spindle speed is increased, the cutting range is increased, and high-speed continuous processing is realized;

(3) By directly cooling the heating part of the main shaft, the sensitivity and timeliness of temperature control are improved, and the service life of parts is increased, and it is suitable for the processing of abrasive tools and other industries, with strong versatility.

Description of drawings

Fig. 1 is a working principle diagram of the mechanical spindle structure of the oil-pneumatic boring bar in the embodiment of the present invention.

Detailed ways

It is easy to understand that, according to the technical solution of the present invention, those skilled in the art can imagine various implementations of the present invention without changing the essence and spirit of the present invention. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the entirety of the present invention or as a limitation or limitation on the technical solution of the present invention.

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and in no way taken as limiting the invention, its application or uses.

Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the description.

In all examples shown and discussed herein, any specific values should be construed as exemplary only, and not as limitations. Therefore, other instances of the exemplary embodiment may have different values.

The invention provides an oil-gas boring bar mechanical main shaft structure, which includes a main shaft casing, a main shaft mandrel, a boring bar, a support bearing, a bearing gland, a dust-proof mechanical labyrinth, a metal cutting tool, a broach mechanism, a hollow internal cooling module, and an oil-air cooling And control device, temperature detection device, speed detection device, of which:

Spindle jacket, fit into the center hole of the machine tool spindle box body with a gap, and connect to the end face;

The main shaft mandrel is arranged inside the main shaft outer cover, and is a rotary part, and the main shaft mandrel is provided with a flat key;

The boring bar is arranged inside the main shaft mandrel, connected with the slot inside the main shaft mandrel, rotates together with the main shaft mandrel, and can be axially displaced;

Support bearings are arranged between the main shaft outer casing and the main shaft mandrel to provide slewing support;

The bearing gland is arranged at the end of the bearing to fix the position of the bearing, and adjust the thickness of the bearing gland to adjust the pretightening force of the supporting bearing, so as to produce different spindle cutting performance;

The dust-proof mechanical labyrinth is arranged between the support bearing and the bearing gland to prevent impurities such as cutting particles and coolant from contaminating the bearing;

Metal cutting tools are set on the end face of the boring bar to cut metal materials;

a broaching mechanism, arranged inside the boring bar, for tensioning the metal cutting tool;

A hollow internal cooling module, placed in the center of the rod of the broach mechanism, to cool the pair of metal cutting tools;

The oil-air cooling and control device is placed outside the main shaft. The oil-air cooling medium passes through the pipeline and the flow channel preset in the main shaft jacket, and the medium enters the inside of the bearing to cool the high-speed bearing;

Temperature detection device for real-time detection of spindle bearing temperature;

The speed detection device is used to detect the real-time rotation speed of the spindle.

As a specific example, in the spindle structure of the oil-pneumatic boring bar machine, the bearing arrangement controls the thermal extension structure, and double-row cylindrical roller bearings are used for radial support at the front and rear ends to enhance the radial cutting rigidity of the spindle.

As a specific example, in the main shaft structure of the oil-gas boring bar machine, the front end adopts the O-shaped support of the oblique support bearing and the double-row cylindrical roller bearing for positioning support; the rear end adopts the double-row cylindrical roller bearing for floating Support; the bearing temperature rises, and the rigid material of the spindle extends to the rear end, which does not affect the spindle accuracy of the front end of the spindle.

As a specific example, in the mechanical spindle structure of the oil-air boring bar, the oil-air lubrication cooling method and the structure of the lifting limit speed are as follows:

The compressed air generated by the air compressor and the ice oil cooled by the oil cooling equipment are passed into the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the internal design passage of the spindle and flows into the bearing position for bearing lubrication and cooling. , The oil and gas are discharged from the labyrinth structure to take away the heat. This method cools down quickly, quickly reaches the thermal equilibrium state, and increases the limit speed.

As a specific example, in the structure of the main shaft of the oil-pneumatic boring bar machine, the telescopic structure of the main shaft of the boring bar is as follows: the boring bar is connected to the main shaft through a sliding flat key, and the circumferential movement of the main shaft and the boring bar is constrained, and the axial direction can be moved in the feed direction. Driven by the screw rod and the motor, it moves axially.

As a specific example, in the oil-air boring bar mechanical main shaft structure, the heat balance control method is: the temperature sensor detects the temperature rise state of the main shaft bearing position in real time, sets the temperature rise interval, and increases the supply of oil-air cooling medium if it is higher than the interval value Rate, to cool down, when the temperature is lower than the interval value, reduce the supply rate of the oil-air cooling medium to stabilize the temperature within the set interval.

As a specific example, the mechanical main shaft structure of the oil-air boring bar specifically includes a boring bar 1, a main shaft 2, a front bearing front gland 3, a front labyrinth ring 4, a cylindrical roller bearing 5, an oil-gas splitting spacer ring 6, an angle Contact bearing 7, front bearing rear gland 8, rear labyrinth ring 9, lock nut 10, tee joint 11, rear bearing outer ring support 12, rear cylindrical roller bearing 13, rear bearing gland 14, pull claw 15 , Pull rod 16, shrapnel 17, shrapnel gland 18, oil-air mixer 19, air compressor 20, oil cooling equipment 21, flat key 22, spindle housing 23, cutter 24.

As a specific example, in the structure of the main shaft of the oil-pneumatic boring bar machine, the boring bar 1 is connected to the main shaft 2 through four flat keys 22 to constrain the circular movement. The gland 18 and the tool 24 move in the axial direction together, and the tool extension processing function is realized through the feed movement; the claw 15 is stretched backward under the preset force of the shrapnel 17, and the tool 24 is tightened;

There are 3 bearings at the front end of the main shaft: 1 cylindrical roller bearing 5, 2 angular contact bearings 7; the outer ring of the bearing is fixed through the front gland 3 of the front bearing and the rear gland 8 of the front bearing, and is locked by the lock nut 10 The preload of the front bearing; the rear bearing is a rear cylindrical roller bearing 13, which is installed on the main shaft 2 and the support member 12 of the outer ring of the rear bearing, which acts as a radial support, and the rear bearing cover 14 locks the bearing to prevent axial movement move.

As a specific example, in the oil-air boring bar mechanical main shaft structure, the compressed air generated by the air compressor 20 and the ice oil cooled by the oil cooling device 21 are passed into the oil-air mixer 19 for mixing, and the flow is divided through the three-way joint 11 , through the main shaft housing 23 and the rear bearing outer ring support member 12, it is connected to the internal design passage of the main shaft to cool down, and the oil and gas are discharged from the front labyrinth ring 4 and the rear labyrinth ring 9.

The present invention also provides a working method of the mechanical spindle structure of the oil-pneumatic boring bar, specifically as follows:

Equipped with cylindrical roller bearings with oil-air boring bar mechanical spindle structure, the front end adopts double-row cylindrical bearings, and 2 large steel ball angular contact spindle bearings are used as positioning bearings for axial and radial support, and the rear end adopts double-row cylindrical bearings as positioning bearings. floating bearing;

Boring bar expansion and contraction: The boring bar is connected to the main shaft through a flat key, restricting the circular movement between the main shaft and the main shaft, and rotating together with the main shaft, and the axial direction moves axially under the action of the propulsion structure. After the metal cutting tool is extended, the internal control process of the box is carried out processing;

Cooling control: The compressed air generated by the air compressor and the ice oil cooled by the oil cooling equipment are mixed with the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the internal passage of the main shaft and flows into the bearing position for bearing lubrication and cooling. Cooling down, the oil and gas are discharged from the labyrinth ring structure to take away the heat.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example

Fig. 1 The structure and cooling control method of the new oil-air boring bar spindle provided by the embodiment of the present invention.

The main shaft structure of the oil-gas boring bar machine specifically includes a boring bar 1, a main shaft 2, a front bearing front gland 3, a front labyrinth ring 4, a cylindrical roller bearing 5, an oil-gas splitting ring 6, an angular contact bearing 7, and a front bearing Rear gland 8, rear labyrinth ring 9, lock nut 10, tee joint 11, rear bearing outer ring support 12, rear cylindrical roller bearing 13, rear bearing gland 14, pull claw 15, pull rod 16, shrapnel 17 , Shrapnel gland 18, oil-air mixer 19, air compressor 20, oil cooling equipment 21, flat key 22, spindle housing 23, cutter 24.

Structural relationship and working principle:

According to the mechanical spindle structure of the oil-gas boring bar, the boring bar 1 is connected with the main shaft 2 through four flat keys 22 to constrain the circular movement. Moving in the same axial direction, through the feed movement, the tool extension processing function is realized; the claw 15 is stretched backward under the preset force of the shrapnel 17, and the tool 24 is tightened;

There are 3 bearings at the front end of the main shaft: 1 cylindrical roller bearing 5, 2 angular contact bearings 7; the outer ring of the bearing is fixed through the front gland 3 of the front bearing and the rear gland 8 of the front bearing, and is locked by the lock nut 10 The preload of the front bearing; the rear bearing is a rear cylindrical roller bearing 13, which is installed on the main shaft 2 and the support member 12 of the outer ring of the rear bearing, which acts as a radial support, and the rear bearing cover 14 locks the bearing to prevent axial movement move.

Cooling principle: The above-mentioned oil-air boring bar mechanical spindle structure, the clean compressed air generated by the air compressor 20 and the ice oil cooled by the oil cooling device 21 are passed into the oil-air mixer 19 for mixing, and the flow is divided through the three-way joint 11. The main shaft casing 23 and the rear bearing outer ring support member 12 are connected to the internal design passage of the main shaft for cooling, and the oil and gas are discharged from the front labyrinth ring 4 and rear labyrinth ring 9 to take away heat.

This type of cylindrical roller bearing configuration with three fronts and one back has strong rigidity and is suitable for gravity cutting. Boring bar 1 can be moved to facilitate deep cavity processing.

This embodiment also provides an oil-air boring bar mechanical spindle structure and cooling control method:

The cylindrical roller bearing configuration of the main shaft structure of the oil-gas boring bar machine in this embodiment adopts double-row cylindrical bearings at the front end and two large steel ball angular contact main shaft bearings as positioning bearings for axial and radial support, and double-row cylindrical bearings at the rear end. Cylindrical bearings are used as floating bearings. With this configuration, the cutting ability is greatly enhanced, the radial rigidity is increased by 50%, and the axial rigidity is increased by 30%. It is suitable for gravity cutting.

Boring bar telescopic function, the boring bar is connected with the main shaft through a flat key, restricting the circular movement between the main shaft and the main shaft, and can rotate together with the main shaft, and the axial direction can move axially under the action of another propulsion structure, and can extend 700 lengths to cut metal The tool extends 700mm in length to process the internal control process of the box.

In the cooling control mode, the clean compressed air generated by the air compressor is mixed with the ice oil cooled by the oil cooling equipment into the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the designed passage inside the spindle and flows into the bearing. Position, lubricate the bearing and cool down, the oil and gas are exhausted from the front labyrinth ring and rear labyrinth ring to take away the heat.

Further, this example can directly carry out oil-air mixing cooling and lubrication on the heating position of the front and rear bearings of the main shaft, through the main shaft temperature detection sensor, detect the real-time temperature of the main shaft, control the temperature of the ice oil and the oiling interval, and establish a temperature compensation model through experimental testing. The temperature of the spindle is controlled within the required range, reducing thermal elongation of the spindle, improving precision and increasing the speed of the spindle.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention.

It should be appreciated that in the foregoing description of exemplary embodiments of the invention, in order to streamline the present disclosure and to assist those skilled in the art in understanding its various aspects, various features of the invention are sometimes described in the context of a single embodiment, or with reference to A single graph is described. However, the present invention should not be interpreted that the features included in the exemplary embodiments are all essential technical features of the patent claims.

Claims (10)

1. An oil-gas boring bar mechanical spindle structure, characterized in that it includes a main shaft cover, a main shaft mandrel, a boring bar, a support bearing, a bearing gland, a dust-proof mechanical labyrinth, a metal cutting tool, a broach mechanism, and a hollow internal cooling module , oil-gas cooling and control device, temperature detection device, speed detection device, of which: Spindle jacket, fit into the center hole of the machine tool spindle box body with a gap, and connect to the end face; The main shaft mandrel is arranged inside the main shaft outer cover, and is a rotary part, and the main shaft mandrel is provided with a flat key; The boring bar is arranged inside the main shaft mandrel, connected with the slot inside the main shaft mandrel, rotates together with the main shaft mandrel, and can be axially displaced; Support bearings are arranged between the main shaft outer casing and the main shaft mandrel to provide slewing support; The bearing gland is arranged at the end of the bearing to fix the position of the bearing, and adjust the thickness of the bearing gland to adjust the pretightening force of the supporting bearing, so as to produce different spindle cutting performance; The dust-proof mechanical labyrinth is arranged between the support bearing and the bearing gland to prevent impurities such as cutting particles and coolant from contaminating the bearing; Metal cutting tools are set on the end face of the boring bar to cut metal materials; a broaching mechanism, arranged inside the boring bar, for tensioning the metal cutting tool; A hollow internal cooling module, placed in the center of the rod of the broach mechanism, to cool the pair of metal cutting tools; The oil-air cooling and control device is placed outside the main shaft. The oil-air cooling medium passes through the pipeline and the flow channel preset in the main shaft jacket, and the medium enters the inside of the bearing to cool the high-speed bearing; Temperature detection device for real-time detection of spindle bearing temperature; The speed detection device is used to detect the real-time rotation speed of the spindle. 2. The main shaft structure of oil-pneumatic boring bar machine according to claim 1, characterized in that, the radial support of the front end and the rear end is carried out by double-row cylindrical roller bearings. 3. The main shaft structure of oil-gas boring bar machine according to claim 2, characterized in that, the front end adopts O-shaped support of oblique support bearing and double-row cylindrical roller bearing for positioning support; the rear end adopts double-row cylindrical roller bearing , for floating support; the bearing temperature rises, and the rigid material of the main shaft extends to the rear end. 4. The oil-air boring bar mechanical spindle structure according to claim 1, characterized in that the oil-air cooling and control device is as follows: The compressed air generated by the air compressor and the ice oil cooled by the oil cooling equipment are passed into the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the internal design passage of the spindle and flows into the bearing position for bearing lubrication and cooling. , the oil and gas are discharged from the labyrinth structure to take away the heat. 5. The main shaft structure of oil-pneumatic boring bar machine according to claim 1, characterized in that the boring bar is connected with the main shaft through a sliding flat key, and the circumferential movement of the main shaft and the boring bar is constrained, and the axial direction can be moved between the feed screw and the motor. Axial movement is carried out under the drive. 6. The main shaft structure of oil-air boring bar machine according to claim 1, characterized in that the temperature sensor detects the temperature rise state of the main shaft bearing position in real time, sets the temperature rise interval, and increases the supply rate of the oil-air cooling medium if it is higher than the interval value. The temperature is lowered, and when the temperature is lower than the interval value, the supply rate of the oil-air cooling medium is reduced to stabilize the temperature within the set interval. 7. The main shaft structure of the oil-pneumatic boring bar machine according to claim 1, characterized in that it specifically comprises a boring bar (1), a main shaft (2), a front bearing front gland (3), a front labyrinth ring (4), a cylinder Roller bearing (5), oil-gas splitting ring (6), angular contact bearing (7), front bearing rear gland (8), rear labyrinth ring (9), lock nut (10), tee joint (11 ), rear bearing outer ring support (12), rear cylindrical roller bearing (13), rear bearing gland (14), pull claw (15), pull rod (16), shrapnel (17), shrapnel gland (18 ), oil-air mixer (19), air compressor (20), oil cooling equipment (21), flat key (22), spindle housing (23), cutter (24). 8. The main shaft structure of the oil-pneumatic boring bar machine according to claim 7, characterized in that the boring bar (1) is connected with the main shaft (2) through four flat keys (22) to constrain the circular movement, and the boring bar (1) Move in the axial direction together with the claw (15), pull rod (16), shrapnel (17), shrapnel gland (18), and tool (24), and realize the tool extension processing function through the feed movement; the pull claw (15) Under the preset force of the shrapnel (17), stretch it backwards to tighten the cutter (24); There are 3 bearings at the front end of the main shaft: 1 cylindrical roller bearing (5), 2 angular contact bearings (7); the bearing outer ring is fixed by the front bearing front cover (3) and the front bearing rear cover (8). The front bearing is preloaded by locking the lock nut (10); the rear bearing is a rear cylindrical roller bearing (13), which is installed on the main shaft (2) and the rear bearing outer ring support (12). To the supporting effect, the rear bearing gland (14) locks the bearing to prevent axial movement. 9. The oil-air boring bar mechanical main shaft structure according to claim 8, characterized in that the compressed air generated by the air compressor (20) and the ice oil cooled by the oil cooling device (21) are passed into the oil-air mixer (19) Mixing, splitting through the three-way joint (11), connecting the main shaft housing (23) and the rear bearing outer ring support (12) to the internal design passage of the main shaft to cool down, and the oil and gas flow from the front labyrinth ring (4) and the rear labyrinth Discharge at ring (9). 10. A working method for the mechanical spindle structure of the oil-pneumatic boring bar according to any one of claims 1 to 9, characterized in that, the details are as follows: Equipped with cylindrical roller bearings with oil-air boring bar mechanical spindle structure, the front end adopts double-row cylindrical bearings, and 2 large steel ball angular contact spindle bearings are used as positioning bearings for axial and radial support, and the rear end adopts double-row cylindrical bearings as positioning bearings. floating bearing; Boring bar expansion and contraction: The boring bar is connected to the main shaft through a flat key, restricting the circular movement between the main shaft and the main shaft, and rotating together with the main shaft, and the axial direction moves axially under the action of the propulsion structure. After the metal cutting tool is extended, the internal control process of the box is carried out processing; Cooling control: The compressed air generated by the air compressor and the ice oil cooled by the oil cooling equipment are mixed with the oil-air mixer to generate a mixture of cooling oil and gas, which is connected to the internal passage of the main shaft and flows into the bearing position for bearing lubrication and cooling. Cooling down, the oil and gas are discharged from the labyrinth ring structure to take away the heat.