CN115647450A - A milling tool, milling equipment and temperature control method based on laser refrigeration - Google Patents

Abstract

The invention discloses a milling cutter based on laser refrigeration, milling equipment and a temperature control method; the milling cutter includes a disc milling cutter and a laser refrigeration module. The laser refrigeration module includes a refrigeration assembly. A cooling unit is installed on each tooth of the disc milling cutter. The cooling assembly includes a flat reflector, a cooling element and a concave reflector. The reflection surfaces of the plane reflector and the concave reflector are opposite to each other and arranged at intervals. A cooling inner cavity is formed between the concave reflector and the plane reflector. The cooling element is arranged in the cooling inner chamber. A through hole is opened on the plane reflector. The through hole on the plane reflector is staggered with the main optical axis of the concave reflector. Several light-transmitting windows are arranged on the side of the cooling element. In the present invention, plane reflection mirrors and concave reflection mirrors are respectively arranged on both sides of the refrigeration element, so that the length of the path that the refrigeration element passes through in the refrigeration element is increased, thereby improving the cooling efficiency of the milling cutter.

Description

A milling tool, milling equipment and temperature control method based on laser refrigeration

technical field

The invention belongs to the technical field of tool cooling, and in particular relates to a milling tool based on laser refrigeration, milling equipment and a temperature control method.

technical background

During the mechanical processing of polymers and biomaterials, the workpiece is deformed by the extrusion of the tool, and there is friction between the workpiece and the tool. This process will generate a large amount of cutting heat. If the cutting heat is not discharged in time, the polymer will disintegrate after being heated. The melting phenomenon will cause thermal deformation, the biological structure in the biological material will be destroyed, and the tool will also undergo thermal wear, which will reduce the life of the tool, resulting in a decrease in machining accuracy, which greatly limits the machining efficiency. At present, in the cutting process, the temperature of the processing area is mainly cooled by means of external refrigeration, such as adding cutting fluid to the cutting area or spraying low-temperature gas. However, the processing of ultra-clean parts such as chips and semiconductors has extremely high requirements on the environment, and impurities are often not allowed to enter the processing area, and a large amount of saline is poured in the cutting of biological materials, which will cause great waste, and the expensive coolant circulation system It will also increase the cost. Tool cooling in machining is facing serious challenges.

The temperature control of the tool tip plays an extremely important role during processing. Laser cooling reduces the thermal movement of atoms in the material by irradiating a specific material with a laser of a specific wavelength, thereby reducing the temperature of the material. It is a clean and efficient cooling method, and its application prospect is very broad, but there are few researches on laser cooling applied to cutting tools. Patent No.: CN212665839U uses laser to irradiate yttrium lithium fluoride crystal or glass to achieve single-point cooling of the cutting area of the grinding wheel. This method spreads the laser through the air, and the complex particles in the air will have an unknown effect on the laser, thereby affecting the cooling effect; in addition, this invention only targets the single-point cooling of the cutting area of the grinding wheel, and the external cooling effect is not good; and the temperature control There is no specific plan.

Contents of the invention

The object of the present invention is to provide a milling tool based on laser refrigeration, milling equipment and temperature control method, so as to realize self-cooling and temperature control of the tool during cutting.

In a first aspect, the present invention provides a laser cooling milling tool, which includes a disc milling cutter and a laser cooling module. The laser refrigeration module includes a refrigeration assembly. A cooling unit is installed on each tooth of the disc milling cutter. The refrigeration assembly includes a plane reflector, a refrigeration element and a concave reflector. The refrigeration element adopts laser refrigeration material. The reflective surfaces of the plane reflector and the concave reflector are opposite to each other and arranged at intervals. A cooling cavity is formed between the concave reflector and the plane reflector. The cooling element is arranged in the cooling inner chamber. A through hole is opened on the plane reflector. The through hole on the plane reflector is staggered with the main optical axis of the concave reflector. Several light-transmitting windows are arranged on the side of the cooling element. During the working process, the laser light enters the cooling inner cavity through the through hole on the plane reflector, and is reciprocally reflected between the plane reflector and the concave reflector.

Preferably, the laser refrigeration module further includes a photoelectric slip ring, a photoelectric hybrid cable and a reflector. The reflector is fixed on the side of the plane reflector away from the concave reflector. The reflective surface of the reflective lens is inclined towards the central axis of the disc milling cutter; one end of the photoelectric hybrid cable is connected with the photoelectric slip ring. The other end of the photoelectric hybrid cable is fixed on the disc milling cutter, and the light exit hole is oriented radially along the disc milling cutter. The laser light emitted from the light exit hole of the photoelectric hybrid cable is reflected by the reflector and then enters the through hole on the plane reflector. During the working process, the laser input from the outside is injected into the cooling inner cavity through the electric slip ring, the photoelectric hybrid cable and the reflector.

Preferably, the laser refrigeration module further includes a temperature detection component. The temperature detection component includes an infrared receiver and an infrared light channel. The infrared light channel is arranged on the side of the cooling assembly. The infrared receiver is arranged at the end of the infrared light channel, and faces the corresponding knife tooth. The signal line of the infrared receiver is led out through the photoelectric hybrid cable and the photoelectric slip ring.

Preferably, the middle part of the photoelectric hybrid cable protrudes to a side close to the central axis of the disc milling cutter.

Preferably, the concave reflector adopts a spherical concave mirror.

Preferably, a heat conduction layer is arranged between the concave reflector and the corresponding knife teeth. The heat conduction layer adopts the flexible heat conduction silicone film.

Preferably, the laser refrigeration material adopts nanometer cadmium sulfide.

In a second aspect, the present invention provides a laser cooling milling device, which includes a frame, a workbench, a milling drive mechanism, the aforementioned milling tool, a fixture, a laser emitter and a control module. Both the table and the milling drive mechanism are mounted on the frame. The jig is installed on the table. The disc milling cutter is mounted on the spindle of the milling drive. The milling drive is provided with a spindle support for mounting the spindle. The photoelectric slip ring is installed between the main shaft support and the main shaft. The signal line of the infrared receiver is connected to the control module through the photoelectric slip ring; the laser output from the laser transmitter is transmitted to each refrigeration component through the input optical fiber and the photoelectric slip ring. The laser transmitter is controlled by the control module.

Preferably, the input optical fiber is an erbium-doped optical fiber.

In a third aspect, the present invention provides a temperature control method for a laser-cooled milling tool during milling, which is specifically as follows:

The workpiece is milled with a disc milling cutter, and the temperature of the teeth of the disc milling cutter rises; the laser is injected into the cooling cavity between the concave reflector and the plane reflector, and reciprocates between the plane reflector and the concave reflector reflection. The anti-Stokes fluorescence produced by the cooling element irradiated by the laser emits through the light-transmitting window to take away heat, and the temperature of the cutter tooth decreases. The infrared receiver detects the infrared intensity radiated by the blade teeth to obtain the temperature of the blade teeth; when the measured temperature is greater than the upper limit of the preset range, the laser power is increased and/or the laser wavelength is reduced. When the measured temperature is less than the lower limit of the preset range, reduce the laser power and/or increase the laser wavelength.

The beneficial effects that the present invention has are:

1. The present invention irradiates semiconductor nanomaterials with specific wavelengths of laser light to excite anti-Stokes fluorescence to reduce the temperature of the cutter head; and, the present invention sets plane reflectors and concave reflectors on both sides of the cooling element, so that the size of the cooling element increases. The length of the path passed in the refrigeration element improves the cooling efficiency of the milling cutter; thereby providing an efficient, vibration-free, clean and pollution-free tool cooling method.

2. The present invention has a light-transmitting window on the side of the cooling inner cavity, which can take away the anti-Stokes fluorescence with heat from the inside of the cutter without affecting the cutting strength of the cutter.

3. The present invention respectively detects the infrared rays radiated by each tooth through an infrared receiver to detect the temperature of the tooth, and adjusts the strength of the cooling effect by adjusting the laser power and wavelength to realize the processing temperature of the milling cutter. The low-latency control can detect and eliminate the failure of the refrigeration system on a certain cutter tooth in time to prevent excessive wear of the cutter due to temperature imbalance.

4. The present invention adopts cadmium sulfide, a II-VI group semiconductor nanomaterial, as the laser refrigeration material, which can still continue to reduce the temperature by 532nm laser irradiation under the low temperature condition of -173°C, and can effectively cool the milling cutter. In addition, the present invention transmits the laser light to the laser cooling module through the gain fiber doped with rare earth element Er3+, the gain fiber has stable transmission efficiency and laser gain effect, and can increase the cooling efficiency.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a schematic diagram of the installation of the refrigeration assembly and the temperature detection assembly in the present invention.

Fig. 3 is a temperature control flow chart of the present invention.

Detailed ways

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

As shown in FIG. 1 , a milling device based on laser cooling includes a frame, a workbench, a milling drive mechanism, a disc milling cutter 5 , a fixture 6 , a laser cooling module and a control module 10 . Both the table and the milling drive mechanism are mounted on the frame. Fixture 6 is installed on the workbench for clamping the workpiece. The disc milling cutter 5 is installed on the main shaft of the milling drive mechanism, and it can rotate and move under the drive of the milling drive mechanism. The milling drive mechanism is provided with a spindle support 7 for mounting the spindle.

The laser cooling module includes an optical fiber connector 1, a photoelectric slip ring 2, an input optical fiber 3, a photoelectric hybrid cable 4, a laser transmitter 9, a cooling component and a temperature detection component. The input optical fiber 3 is an erbium-doped optical fiber. The optical fiber connector 1 is fixed on the spindle support 7 . The fixed portion of the photoelectric slip ring 2 is fixed to the main shaft support 7 . The rotating part of the photoelectric slip ring 2 is fixed to the main shaft. The fixed part of the photoelectric slip ring 2 is provided with a light inlet, and the rotating part is provided with n light outlets. N is the number of cutter teeth 19 of disc milling cutter 5; all light outlets on the photoelectric slip ring 2 are all conducted with light inlets. The light inlet of photoelectric slip ring 2 is connected with the laser output interface of laser transmitter 9 by optical fiber joint 1 and input optical fiber 3. The control module 10 includes a controller and a laser signal generator. The signal output interface of laser signal generator is connected with the control interface of laser emitter 9. The controller adjusts the laser intensity and wavelength output by the laser emitter 9 through the laser signal generator.

As shown in FIG. 2 , a refrigeration component and a temperature detection component are installed on the top of each tooth 19 of the disc milling cutter 5 . The n cooling assemblies are respectively connected to the n light outlets of the photoelectric slip ring 2 through the optical transmission core wires of n photoelectric hybrid cables 4 . The cooling assembly includes a laser emitting hole 11 , a reflector 13 , a plane reflector 15 , a cooling element 16 , a light-transmitting window 17 , a heat conduction layer 18 , knife teeth 19 and a concave reflector 20 .

The cooling element 16 adopts a laser cooling material, which can release fluorescence and lower the temperature under the irradiation of laser light with a specific emission wavelength. The heat conduction layer 18 adopts a flexible heat conduction silica gel sheet. The laser cooling material is cadmium sulfide, a semiconductor nanomaterial. In this embodiment, the semiconductor nanomaterial cadmium sulfide is specifically a II-VI semiconductor nanometer cadmium sulfide material, and its emission wavelength is 500-550 nm.

The concave reflector 20 is a spherical concave mirror; the back of the concave reflector 20 and the top surface of the corresponding cutter teeth 19 on the disc milling cutter 5 are fixed through the heat conduction layer 18 . The concave reflective surface of the concave reflector 20 faces directly upward. The plane reflector 15 that reflective surface is arranged downward is fixed on the disc milling cutter 5, and is positioned at the top of concave reflector 20. A cooling inner cavity is formed between the concave reflector 20 and the plane reflector 15. The cooling element 16 is arranged in the cooling inner cavity. The middle part of the plane mirror 15 is provided with a through hole. The through hole on the plane reflector 15 is staggered with the main optical axis of the concave reflector 20, so that the laser light injected from the through hole on the plane reflector 15 will not be reflected directly from the plane reflector 15 after the concave reflector 20 is once reflected. through-hole injection on the The side of the cooling element 16 is provided with one or more light-transmitting windows 17, which will not affect the cutting strength of the cutter teeth. The light-transmitting window 17 is used to release the fluorescence generated by the cooling element 16 under laser irradiation, thereby releasing heat.

An optical fiber connection block of transparent material is fixed on the top surface of the flat reflector. The reflective mirror 13 is arranged inside the fiber connection block. The reflective surface of the reflective mirror 13 is inclined towards the disc milling cutter 5, and forms an angle of 45° with the horizontal plane; the photoelectric hybrid cable 4 is fixed with the corresponding optical fiber connection block, and the light exit hole 10 is arranged radially along the disc milling cutter 5 , and towards the reflective surface of the mirror 13 . The laser light emitted from the light exit hole 10 of the photoelectric hybrid cable 4 is reflected by the reflector 13 and then enters the through hole on the plane reflector 15. The laser light reflected by the reflective mirror 13 is parallel to the main optical axis of the concave reflector 20 .

The input end of the photoelectric hybrid cable 4 is arranged vertically upwards, and the output end is arranged outwardly along the radial direction of the disc milling cutter, and the middle part protrudes to a side near the central axis of the disc milling cutter. During the high-speed rotation of the disc milling cutter, the photoelectric hybrid cable 4 protruding inward can use its own elasticity to offset the influence of centrifugal action and improve the stability of the laser refrigeration module.

During the working process, the laser emitted by the laser emitting head 9 will enter the cooling inner cavity through the input optical fiber 3, the optical fiber connector 1, the photoelectric slip ring 2, the photoelectric hybrid cable 4 and the reflector. The incident laser light (solid line) entering the cooling cavity passes through the cooling element. After the cooling element is irradiated by the laser, it will produce a cooling effect; the laser will reflect the laser multiple times (dotted line part) between the flat/concave mirror combination in the cooling cavity to enhance the cooling efficiency. The anti-Stokes fluorescence that the cooling element is irradiated by the laser emits and takes away heat through the light-transmitting window 17, thereby realizing the cooling effect on the cutter teeth.

The temperature detection component includes an infrared receiver 12 and an infrared light channel 14 . Infrared light channel 14 is arranged on the side of refrigeration assembly. The infrared receiver 12 is fixed on the side of the photoelectric hybrid cable 4 and aligned with the end of the infrared light channel 14 . The infrared receiver 12 is directed towards the knife tooth 19 through the infrared light channel 14, and collects the infrared rays radiated by the knife tooth 19, thereby realizing the temperature detection of the knife tooth 19. The signal output interface of each infrared receiver 12 is connected to the controller of the control module 10 through the electric core wire in the corresponding photoelectric hybrid cable 4 , the electrical transmission interface of the photoelectric slip ring 2 and the temperature signal transmission cable 8 . The controller obtains the temperature of each cutter tooth according to the electrical signal output by the infrared receiver 12, thereby adjusting the laser wavelength emitted by the laser transmitter.

Concrete implementation process of the present invention is as follows:

The control module 10 excites a laser with a wavelength of 500-550nm; the laser is emitted by the laser transmitter 9, and the laser is irradiated to the fiber joint 1 through the input optical fiber 3; the input optical fiber 3 can transmit the laser stably, and at the same time, the laser is transmitted due to the input The absorption of the rare earth medium in the optical fiber 3, the energy carried by the incident light will excite the electrons in the medium to a higher energy level, and a relaxation phenomenon will occur. The electrons release energy by transitioning from a high energy level to the ground state, and emit photons, which enhances the flow of photons and improves the cooling efficiency. The laser light is irradiated to the reflective mirror 13 after being emitted from the light exit hole of the photoelectric hybrid cable, and the incident laser light is reflected to the cooling element 16. After the cooling element 16 is irradiated by the laser with a specific wavelength, the thermal motion of the atoms therein will be hindered by the photons in the laser, and its temperature will drop. When the incident laser light hits the concave lens 17 at the bottom of the cooling element, it will be reflected to the plane mirror 13 above it. Such multiple reflections increase the laser irradiation distance, and the laser cooling efficiency is enhanced. At the same time, the cooling element 16 will excite anti-Stokes fluorescence which is smaller than the wavelength of the incident laser light, and the fluorescence is emitted through the light-transmitting window 17 to take away heat. The cold energy generated by the refrigeration element is transmitted to the cutter teeth 19 through the heat conduction layer 18, thereby realizing the cooling of the cutter teeth 19. Simultaneously, the heat-conducting layer 18 of flexible material can play a role in buffering and protecting the cooling element 16 when the cutter teeth 19 perform cutting operations.

The process and conditions for refrigeration element 16 to produce refrigeration effect are as follows:

1. The cooling element absorbs photons and thermally relaxes (absorbs heat): the atoms with the same wavelength as the laser photon and the thermal motion in the cooling element will combine together.

2. The refrigeration element spontaneously radiates fluorescent photons and thermal relaxation (release heat): the atoms undergo energy level transitions, their own motion speed decreases, and then the photons are emitted to the opposite direction of the atomic motion, and at the same time act on an impulse in the opposite direction of the atom. The movement speed of the atoms is further reduced, and the heat movement speed of the atoms inside the cooling element is reduced.

3. The cooling element absorbs a laser photon with energy hν, emits a fluorescent photon with an average energy of hν _f , and takes away the heat energy of hν _f -hν, where hν _f is the average energy of fluorescent radiation, and each refrigeration cycle process The cooling power P _cool is:

Among them, P _abs is the resonant absorbed power density. λ is the wavelength of the incident light, λ _f is the wavelength of the reflected fluorescence, and when the wavelength of the incident light is greater than the average wavelength of the fluorescence, that is, λ>λ _f , laser cooling can be realized.

The reflected anti-Stokes fluorescence is emitted through the light-transmitting window of the cutter to remove heat from the cooling element.

As shown in Figure 3, the method for controlling the temperature of the milling equipment based on laser cooling during the milling process is as follows:

Temperature control process: As the cutting operation progresses, the cutter teeth 19 will generate heat due to friction and extrusion with the workpiece, and the cutter teeth 19 will radiate thermal infrared rays. The energy of infrared rays is related to the temperature of the cutter teeth 19. The energy of infrared rays at different temperatures will change.

Input the preset temperature T0, use the preset temperature T0 as the temperature reference of the cutter tooth 19, and then start the cutting operation.

Along with the carrying out of cutting operation, cutter tooth 19 can produce cutting heat temperature rise, and the infrared ray that it produces is irradiated to the infrared receiver 12 (dot-dash line part) that is installed in the photoelectric hybrid cable 4 bottoms through light-transmitting hole 14, and infrared receiving The device 12 converts the optical signal into an electrical signal after receiving the infrared light radiated by the knife tooth 19 .

Then the photoelectric hybrid cable transmits the electric signal to the signal processing module integrated in the control module 10, and obtains the current temperature of the knife tooth 19 after the signal is processed. When the temperature of cutter tooth 19 exceeds preset value certain scope, control module starts to carry out temperature regulation.

When the temperature is too high, first increase the laser power to enhance the efficiency of laser cooling, while reducing the laser wavelength. Strengthening the laser power can significantly reduce the temperature. At the same time, due to the temperature rise of the cooling element, the thermal motion speed of the internal atoms increases, and its wavelength is shorter than before. At this time, it is necessary to reduce the laser wavelength to excite more fluorescence to reduce the temperature.

If the temperature of the cutter teeth is too low, the lower temperature cutter teeth are prone to stress damage during the cutting process. Therefore, at this time, the temperature of the cutter teeth is increased by adjusting the control module. At this time, only the power of the incident laser is reduced, and the temperature of the cooling element slows down. pick up.

Claims (10)

1. A milling tool based on laser cooling, comprising a disc milling cutter (5); It is characterized in that: it also includes a laser cooling module; the laser cooling module includes a cooling assembly; each of the disc milling cutters (5) A cooling assembly is installed on the cutter teeth (19); the cooling assembly includes a plane reflector (15), a cooling element (16) and a concave reflector (20); the cooling element (16) adopts a laser cooling material The reflective surfaces of the plane reflector (15) and the concave reflector (20) face each other and are arranged at intervals; the cooling inner cavity is formed between the concave reflector (20) and the plane reflector (15); the cooling element ( 16) It is arranged in the cooling inner cavity; a through hole is provided on the plane reflector (15); the through hole on the plane reflector (15) is staggered from the main optical axis of the concave reflector (20); the cooling element (16) There are several light-transmitting windows (17) on the side; during the working process, the laser enters the cooling inner cavity from the through hole on the plane reflector (15), and passes between the plane reflector (15) and the concave reflector (20). reciprocating reflection. 2. A milling tool based on laser refrigeration according to claim 1, characterized in that: said laser refrigeration module also includes a photoelectric slip ring (2), a photoelectric hybrid cable (4) and a reflector (13); The reflector (13) is fixed on the side of the plane reflector (15) away from the concave reflector (20); the reflection surface of the reflector (13) is inclined towards the central axis of the disc milling cutter (5); the photoelectric hybrid cable (4 ) is connected to the photoelectric slip ring (2); the other end of the photoelectric hybrid cable (4) is fixed on the disc milling cutter (5), and the light exit hole (10) faces the radial direction along the disc milling cutter (5) Setting; the laser light emitted from the light exit hole (10) of the photoelectric hybrid cable (4) is reflected by the reflector (13) and injected into the through hole on the plane reflector (15); The ring (2), the photoelectric hybrid cable (4), and the reflector (13) inject into the cooling inner cavity. 3. A milling tool based on laser refrigeration according to claim 2, characterized in that: the laser refrigeration module also includes a temperature detection assembly; the temperature detection assembly includes an infrared receiver (12) and an infrared light channel (14); the infrared light channel (14) is arranged on the side of the cooling assembly; the infrared receiver (12) is arranged at the end of the infrared light channel (14), and faces the corresponding knife tooth (19); the infrared receiver The signal line of (12) is drawn through photoelectric hybrid cable (4) and photoelectric slip ring (2). 4. A milling tool based on laser refrigeration according to claim 1, characterized in that: the middle part of the photoelectric hybrid cable (4) protrudes to the side close to the central axis of the disc milling cutter. 5. A milling tool based on laser refrigeration according to claim 1, characterized in that: the concave mirror (20) adopts a spherical concave mirror. 6. A milling tool based on laser refrigeration according to claim 1, characterized in that: a heat conduction layer (18) is arranged between the concave reflector (20) and the corresponding cutter teeth (19); Layer (18) adopts flexible heat-conducting silica gel sheet. 7. A milling tool based on laser cooling according to claim 1, characterized in that: the laser cooling material is made of nanometer cadmium sulfide. 8. A milling equipment for laser refrigeration, comprising a frame, a workbench, a milling drive mechanism, a fixture (6) and a control module (10); it is characterized in that: it also includes a laser emitter (9) and as claimed in claim 1- The milling tool described in any one of 7; the workbench and the milling drive mechanism are all installed on the frame; the clamp (6) is installed on the workbench; the disc milling cutter (5) is installed on the milling drive mechanism on the main shaft; the milling drive mechanism is provided with a main shaft support (7) for installing the main shaft; the photoelectric slip ring (2) is installed between the main shaft support (7) and the main shaft; the signal line of the infrared receiver (12) passes through the photoelectric The slip ring (2) is connected to the control module; the laser output from the laser transmitter (9) is transmitted to each refrigeration component through the input optical fiber (3) and the photoelectric slip ring (2); the laser transmitter (9) is controlled by the control module. 9. A milling device based on laser refrigeration according to claim 1, characterized in that: the input optical fiber (3) is an erbium-doped optical fiber. 10. A temperature control method in the milling process, characterized in that: use the disc milling cutter (5) in the milling tool according to any one of claims 1-7 to mill the workpiece, the disc milling cutter (5) The cutter tooth temperature rises; the laser light enters the cooling inner cavity between the concave reflector (20) and the plane reflector (15), and between the plane reflector (15) and the concave reflector (20) reciprocating reflection; the anti-Stokes fluorescence produced by the cooling element being irradiated by laser light is emitted through the light-transmitting window (17) to take away heat, and the temperature of the blade teeth is reduced; the infrared receiver (12) detects the infrared intensity radiated by the blade teeth, and obtains The temperature of the cutter tooth; when the measured temperature is greater than the upper limit of the preset range, increase the laser power and/or reduce the laser wavelength; when the measured temperature is less than the lower limit of the preset range, reduce the laser power and/or increase laser wavelength.

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