Gun drill camshaft ultra-deep hole machining process

Abstract

The invention discloses a gun drill camshaft ultra-deep hole machining process which comprises the steps of preparing water-based cutting fluid, assembling a camshaft ultra-deep hole machining system and injecting fluid, cooling the water-based cutting fluid, supplying the fluid at high pressure, drilling, recycling and regenerating the water-based cutting fluid and the like. The application problem of the water-based cutting fluid in gun drill deep hole machining is successfully solved, the water-based cutting fluid is superior to a traditional oil-based cutting fluid technology in the aspects of cost, machining quality and machining efficiency, high-precision and high-quality machining is guaranteed, meanwhile, green, energy-saving and low-cost batch production is achieved, and a more economical and sustainable solution is provided for engine camshaft manufacturing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of camshaft ultra-deep hole machining, in particular to a gun drill camshaft ultra-deep hole machining process. BACKGROUND

[0002] The camshaft is the core component of the engine, which controls the opening and closing action of the valve, and the quality of the camshaft deep hole machining directly affects the performance of the engine. The existing camshaft deep hole machining mostly adopts the gun drill process, because the gun drill has a narrow chip removal space (the gap between the drill rod and the hole wall is only 0.1-0.3mm) and poor heat dissipation, the industry generally uses cutting oil as the cooling and lubricating medium, but this method has the following problems: first, the cost is high, the unit price of cutting oil is 1108 yuan / 100KG, using cutting oil as the cooling and lubricating medium will increase the engine manufacturing cost; second, the pollution is serious, the cutting oil has strong viscosity (5-20mm² / s, 40℃), which is easy to adhere to the surface of the equipment and workpiece, and the residual oil brought into the later process will pollute the cutting fluid, forming a vicious cycle of cleaning-pollution-re-cleaning; in addition, there are technical limitations, the industry generally believes that the gun drill machining deep hole cannot use water-based medium, the core pain point is that the specific heat capacity of water is large but the boiling point is low, which is easy to boil and affect heat dissipation; the viscosity of water is much lower than that of oil, and it is difficult to carry iron chips; and water has no low-temperature lubricating component, which will increase the tool wear, experiments have proved that if the existing water-based medium is used for camshaft deep hole machining, the tool wear is more than twice that of oil-based medium when machining to 180 pieces. In order to solve the above technical problems, it is necessary to develop a new gun drill camshaft ultra-deep hole machining process. SUMMARY

[0003] In order to solve the above problems, the present application provides a gun drill camshaft ultra-deep hole machining process, which comprises: Preparation of water-based cutting fluid: 2-4 parts of emulsifier are added to 74-86 parts of water according to the mass fraction, stirred until completely dissolved, and 8-12 parts of oil agent are added in 3-5 times under stirring, with an interval of 5-10 minutes each time, and then 2.5-5.5 parts of extreme pressure agent, 0.5-1.5 parts of antirust agent, 0.5-1.5 parts of preservative and 0.5-1.5 parts of defoaming agent are added in turn and stirred for 10-20 minutes, and then left for 1-3 hours; the kinematic viscosity of the water-based cutting fluid under the condition of 40℃ is 8-12mm² / s, the pH value is 8-10, and the natural evaporation loss rate in 30 days is ≤5%; The emulsifier can realize stable emulsification of oil and water, form uniform microemulsion or emulsion, prevent oil and water separation, improve the stability and wettability of the water-based cutting fluid, and enhance the spreading ability of the water-based cutting fluid on the metal surface; the oily agent can improve the lubricating property, reduce the friction between the tool and the workpiece, reduce the cutting heat and tool wear, form an adsorption film under medium and low temperature conditions, and improve the boundary lubrication effect; the extreme pressure agent can react with the metal surface under high temperature and high pressure to form a protective film such as iron sulfide and iron phosphide, prevent the gun drill tool from sticking to the camshaft surface, and prolong the service life of the gun drill tool; the rust inhibitor can have excellent corrosion inhibition effect on iron, copper and other metals, protect the inner wall of the camshaft and machine tool parts from rusting; the corrosion inhibitor can inhibit the growth of bacteria and fungi and other microorganisms, prevent the water-based cutting fluid from deteriorating, and prolong the service life; the defoaming agent can inhibit the generation of foam to avoid the influence of foam on the liquid supply pressure, cooling efficiency and liquid level monitoring; batch addition of the oily agent can improve the emulsification efficiency and prevent uneven emulsification or local high concentration caused by one-time mixing; standing helps bubble escape and system stability; appropriate viscosity ensures the balance between flowability and lubricity, which is beneficial to high-pressure conveying and penetration; the pH value of 8-10 is a weak alkaline environment, which can inhibit acid corrosion and protect the skin of the operator; the water-based cutting fluid is not easy to volatilize, which can reduce the frequency of liquid supplement and reduce the cost; the water-based cutting fluid prepared by the application has high stability, excellent cooling and lubricating performance, strong extreme pressure resistance, good rust and corrosion prevention effect, is not easy to foam, and is environmentally friendly and durable, and the cost is lower and the effect is better than that of the oil-based cutting fluid. Assembling the camshaft ultra-deep hole machining system and injecting liquid: the camshaft ultra-deep hole machining system comprises a machine tool 0, a gun drill tool 1, a liquid storage device 4, a temperature control device 5, a high-pressure liquid supply device 6, a chip removal and recovery device 7, a filtration and purification device 8, and a circulating conveying device 9, and each component is connected through a pipeline; the water-based cutting fluid is injected into the liquid storage device 4; Cooling the water-based cutting fluid: starting the temperature control device 5 to cool the water-based cutting fluid to 8-25℃, the low-temperature water-based cutting fluid can effectively take away heat, prevent the gun drill tool 1 from overheating and softening or chipping, improve the size accuracy and straightness of the ultra-deep hole, in addition, the low temperature can significantly slow down the reproduction speed of bacteria and fungi, prolong the service life of the water-based cutting fluid; in addition, the low temperature is also conducive to maintaining the viscosity of the water-based cutting fluid, ensuring that the water-based cutting fluid maintains the best physical and chemical properties at all times, is always in the best working condition, and improves the machining quality; High-pressure liquid supply and drilling processing: start the high-pressure liquid supply device 6, and the water-based cutting fluid cooled is delivered to the gun drill tool 1 at a pressure greater than 3 MPa; the camshaft 3 is drilled by the gun drill tool 1; the gun drill tool 1 includes a drill rod and a drill bit, the drill bit is provided with at least one cutting edge 11 for drilling the camshaft 3, the side of the drill rod close to the drill bit is provided with at least one liquid injection hole 12 inclined to the cutting area, the inside of the drill rod is provided with a liquid supply channel 13, the liquid injection hole 12 is communicated with the liquid supply channel 13, and the water-based cutting fluid is sprayed from the liquid injection hole 12 to the gap between the gun drill tool 1 and the hole wall of the camshaft 3 through the liquid supply channel 13 during processing, so as to cool and lubricate the gun drill tool 1; the outer periphery of the gun drill tool 1 is provided with an axial extending chip removal channel 14, under the action of high-pressure liquid flow, the chip is flushed out along the gap between the gun drill tool 1 and the hole wall of the camshaft 3, and enters the chip removal and recovery device 7 along the chip removal channel 14; The water-based cutting fluid delivered at a pressure greater than 3 MPa can ensure that the water-based cutting fluid reaches the cutting area to lubricate the gun drill tool 1, and at the same time, enough energy is ensured to push the chip to be smoothly discharged, so as to prevent blockage; the liquid injection hole 12 inclined to the cutting area can realize precise directional injection, maximize the cooling and lubricating efficiency, flush the cutting area, and remove the accumulated chips; the internal chip removal mechanism is formed by using the high-pressure liquid flow to forcibly flush the chip out of the peripheral chip removal channel 14 of the gun drill tool 1, and this design is specially suitable for the ultra-deep hole processing scene with a length-diameter ratio of up to 30-35 times; Water-based cutting fluid recovery and regeneration: the water-based cutting fluid containing chips is collected by the chip removal and recovery device 7, and then is filtered by the filtering and purifying device 8; the purified water-based cutting fluid is sent back to the liquid storage device 4 by the circulating delivery device 9 for recycling, and when the PH value of the recycled water-based cutting fluid is less than or equal to 7, the rust inhibitor is supplemented until the PH value of the water-based cutting fluid is restored to 8-10. The filtering and purifying device 8 can remove the impurities such as chips, metal powder and oil sludge wrapped in the water-based cutting fluid, so as to keep the cutting fluid clean, prevent the liquid injection hole 12 from being blocked, and prolong the service life of the gun drill tool 1; the circulating delivery device 9 sends the purified water-based cutting fluid back to the liquid storage device 4 to realize the continuous circulation of the water-based cutting fluid in the system, and improve the continuous operation capacity of the system; the PH value of the water-based cutting fluid is adjusted by actively supplementing the rust inhibitor to restore the physical and chemical properties of the water-based cutting fluid, prolong the service life, reduce consumption and waste liquid discharge; through the cooperative work of the above components, the closed-loop operation of “cooling-liquid supply-chip removal-purification-recycling” can be realized, and the efficient, stable and long-time ultra-deep hole processing demand can be met.

[0004] Preferably, in the step of preparing the water-based cutting fluid, the emulsifier is selected from sodium dodecyl benzene sulfonate (LAS), the oily agent is selected from mineral oil, the extreme pressure agent is selected from sulfur-phosphorus compound extreme pressure agent, the rust inhibitor is selected from water-soluble benzotriazole, the preservative is selected from isothiazolinone preservative, and the defoaming agent is selected from organic silicon polyether defoaming agent.

[0005] Preferably, the gun drill tool 1 is arranged on the machine tool 0, the camshaft 3 is clamped on the machine tool 0 and arranged at the output end of the gun drill tool 1; the liquid storage device 4 comprises a first water tank 41 and a second water tank 42, the newly prepared water-based cutting fluid is stored in the second water tank 42, and the first water tank 41 is used to receive the recycled purified water-based cutting fluid; the temperature control device 5 is connected with the second water tank 42, and a temperature sensor is arranged thereon for monitoring the cooling temperature of the water-based cutting fluid; the high-pressure liquid supply device 6 comprises a high-pressure flushing pump, which is arranged on the pipeline between the second water tank 42 and the gun drill tool 1, and is used to pump the cooled and purified water-based cutting fluid to the gun drill tool 1, and the water inlet of the gun drill tool 1 is provided with a flowmeter 15 for real-time monitoring of the flow of the water-based cutting fluid, ensuring that the diameter of the flow supply channel 13 is matched, and timely discovering blockage or leakage; the chip removal and recycling device 7 comprises a water return groove arranged below the gun drill tool 1, and the water outlet of the water return groove is communicated with the water inlet of the filtering and purifying device 8 through a water pipeline; the water outlet of the filtering and purifying device 8 is communicated with the first water tank 41, and the first water tank 41 is connected with the second water tank 42 through the circulating conveying device 9, which conveys the filtered water-based cutting fluid from the first water tank 41 to the second water tank 42, realizing the continuous circulation of the water-based cutting fluid in the system. The double-tank design can realize hierarchical management of the liquid, ensure the quality of the liquid supply, and ensure that sufficient, clean and temperature-appropriate water-based cutting fluid is always supplied to the gun drill tool 1, thereby fundamentally eliminating the machining quality problems caused by unclean liquid or excessively high temperature, and facilitating centralized treatment and pH value monitoring of the circulating liquid.

[0006] Preferably, the machine tool 0 is provided with a through-hole drill bushing 2, which is located between the camshaft 3 and the gun drill tool 1 and is in clearance fit with the gun drill tool 1; during machining, the gun drill tool 1 penetrates through the through-hole drill bushing 2 and drills the camshaft 3, the through-hole drill bushing 2 guides the gun drill tool 1 to accurately enter the camshaft 3, avoiding deviation from the target drilling position, and secondly supporting the slender gun drill tool 1 to prevent bending, vibration or fracture of the gun drill tool 1 during machining, which is the key to realizing the drilling straightness <0.04mm / m and the surface roughness Ra value <1.2μm. Since the lubricity of the water-based cutting fluid is not as good as that of oil, the risk of friction and wear between the gun drill tool 1 and the through-hole drill bushing 2 increases, and the gun drill tool 1 is provided with a chip removal channel 14 extending in the axial direction, so as to form a clearance fit with the through-hole drill bushing 2. This design not only provides necessary support for the slender gun drill tool 1, but also maximizes the contact area and friction between the two; in addition, due to the lower viscosity and poor chip wrapping ability of the water-based cutting fluid, it is easy to block the chips once the chip removal is not smooth, so this clearance fit design is an important part of ensuring the stability of the high-pressure water-based cutting fluid flow field, and is the key to successfully changing the oil-based cutting fluid system drilling process into the water-based cutting fluid system drilling process.

[0007] Preferably, the over-circulation conveying device 9 is an immersed multi-stage centrifugal pump.

[0008] Preferably, the temperature control device 5 comprises a water chiller.

[0009] Preferably, the filtering and purifying device 8 is a rubber roller type magnetic separator.

[0010] Preferably, the output pressure of the high-pressure flushing pump needs to be controlled at more than 3 MPa, continuously operated for 24 hours, and the pressure fluctuation is less than or equal to ±0.1 MPa, and the chip removal flow rate needs to be greater than or equal to 8.8 m / s. The stable pressure ensures the continuous and effective cooling and chip removal power, and the chip removal flow rate greater than or equal to 8.8 m / s is the key threshold to ensure that the chips are completely flushed out, which can prevent the chip jamming accident.

[0011] Preferably, the rotation speed of the gun drill tool 1 is 1500-2500 r / min, and the feed rate is 0.1-0.2 mm / r. The high rotation speed combined with the medium to low feed rate per revolution can realize efficient shearing cutting to form small and regular "C" chips, which are easier to be flushed away by the high-pressure liquid flow. At the same time, this parameter combination can effectively control the cutting force and cutting heat, ensuring the efficiency while taking into account the service life of the gun drill tool 1 and the drilling quality.

[0012] Preferably, the super deep hole has a depth of 300-700 mm, a diameter of 10-20 mm, a length-diameter ratio of 30-35 times, a straightness of less than 0.04 mm / m, and a surface roughness Ra value of less than 1.2 μm.

[0013] The beneficial effects are that the application provides a gun drill camshaft super deep hole machining process, which successfully realizes the deep hole machining technology breakthrough of replacing the traditional oil-based cutting fluid with the water-based cutting fluid by formulating a special high-performance water-based cutting fluid and constructing a closed-loop machining system.

[0014] The prepared water-based cutting fluid has a moderate viscosity of 8-12 mm² / s, a pH value of 8-10, and excellent cooling, lubricating, extreme pressure, anti-rust, and antibacterial properties, and the cost is only 1 / 12.5 of that of the oil-based cutting fluid, which significantly reduces the cutting fluid procurement cost. At the same time, its low volatility and recycling characteristics can reduce the frequency of liquid supplement and waste liquid treatment cost, and overall reduce the engine manufacturing cost. Secondly, the environmental protection is outstanding. The viscosity of the water-based cutting fluid is moderate (8-12 mm² / s), which is not easy to adhere to the equipment, can avoid the pollution and circulation problems caused by the oil-based cutting fluid, improve the working environment, and reduce the cleaning burden. Technically, the application difficulty of the water-based cutting fluid in gun drill deep hole machining is successfully solved. Through the synergistic effect of emulsifiers, oil agents, extreme pressure agents, and other components, the water-based cutting fluid has excellent cooling and lubricating properties and extreme pressure resistance. Experimental results show that the tool life is significantly improved, and the wear amount is lower than that of the oil-based medium. At the same time, the low-temperature cooling of 8-25℃ effectively inhibits the overheating of the gun drill tool and the bacterial reproduction, ensuring the machining stability. The processing system adopts low-temperature (8-25℃) liquid supply, high-pressure (>3MPa) delivery, directional spray hole and gap cooperation design to ensure sufficient cooling and lubrication of the cutting area, and to efficiently discharge the chips at a speed of ≥8.8m / s to avoid chip clogging; the through-hole drill sleeve cooperates with the chip removal channel to effectively support the gun drill tool, reduce friction and stabilize the liquid flow field; the synergistic effect of various designs realizes high-precision machining of ultra-deep holes (length-diameter ratio 30-35 times), with a hole straightness of <0.04mm / m and a surface roughness Ra of <1.2μm; in addition, the closed-loop circulation system (cooling-liquid supply-chip removal-purification-reuse) maintains the performance of the cutting fluid through filtration and pH adjustment, prolongs the service life of the cutting fluid, reduces waste liquid discharge, improves production continuity and resource utilization; the process is superior to the traditional oil-based cutting fluid process in terms of cost, machining quality and machining efficiency, and realizes green, energy-saving and low-cost mass production while ensuring high-precision and high-quality machining, providing a more economical and sustainable solution for engine camshaft manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0015] The drawings described herein are intended to provide further understanding of the present application, form a part of the present application, and the illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings: Figure 1 is a schematic diagram of the overall structure of the present application; Figure 2 is a schematic diagram of the position of the gun drill tool and the camshaft of the present application; Figure 3 is a schematic diagram of the assembly structure of the gun drill tool and the through-hole drill sleeve of the present application; In the drawings: 0, machine tool; 1, gun drill tool; 11, cutting edge; 12, liquid injection hole; 13, liquid supply channel; 14, chip removal channel; 15, flow meter; 16, spindle motor; 2, through-hole drill sleeve; 3, camshaft; 4, liquid storage device; 41, primary water tank; 42, secondary water tank; 5, temperature control device; 6, high-pressure liquid supply device; 7, chip removal and recovery device; 8, filtration and purification device; 9, circulation delivery device. DETAILED DESCRIPTION

[0016] The following drawings disclose several embodiments of the present invention. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0017] It should be noted that all directional indications in the embodiments of this invention, such as up, down, left, right, front, back, etc., are only used to explain the relative positional relationships and movement of the components in a specific posture as shown in the accompanying drawings. If the specific posture changes, the directional indications will also change accordingly. Furthermore, descriptions involving "first-level," "second-level," etc., in this invention are for descriptive purposes only and do not specifically refer to order or sequence, nor are they intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0018] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The following embodiments are only used to illustrate the present invention, and are not intended to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0019] Raw material source: Sulfur-phosphorus composite extreme pressure agent: Triphenyl thiophosphate, model T309; Ammonium thiophosphate, model T307; both purchased from Jinzhou Chenghua New Materials Co., Ltd.; Sulfur-phosphorus dual nitrogen-containing derivative, model T305, purchased from Nanjing Changchi Lubrication Technology Co., Ltd. Water-soluble benzotriazole (BTA), purchased from Shandong Duoju Chemical Co., Ltd. Isothiazolinone preservatives: Methylisothiazolinone (MIT), purchased from Shandong Kason New Material Co., Ltd.; 5-chloro-2-methyl-isothiazolin-3-one (CMIT), purchased from Hubei Xinjiecheng Chemical Technology Co., Ltd. Silicone polyether defoaming agent, purchased from Shandong Jinrong Chemical Technology Co., Ltd.; Device source: Water cooling machine, model Y LJ250A, purchased from Wuxi Walder Precision Industry Co., Ltd.; High-pressure flushing pump, brand MOOG, model D953-2199, purchased from Shenzhen Parker Hydraulic Industry Co., Ltd.; Rubber roll type magnetic separator, model B1A300, purchased from Yantai Qiyang Machinery Co., Ltd.; Submerged multistage centrifugal pump, purchased from Nanfang Pump Industry Co., Ltd.; HTT numerical control deep hole drilling machine, model K20-4-500, purchased from Shanghai Ningyuan Precision Machinery Co., Ltd.; The rest of the raw materials and devices are all conventional market sales.

[0020] Example 1 This example provides a gun drill camshaft ultra-deep hole machining process: Prepare water-based cutting fluid: add 2 parts of emulsifier to 86 parts of water according to mass fraction, stir until completely dissolved, and under stirring, add 8 parts of oil agent in 3 times, with an interval of 5 min each time, then add 2.5 parts of extreme pressure agent, 0.5 parts of anti-rust agent, 0.5 parts of preservative and 0.5 parts of defoaming agent in turn, mix and stir for 10 min, and stand for 1 h; The kinematic viscosity of the water-based cutting fluid under the condition of 40℃ is 8mm² / s, the pH value is 8, and the 30-day natural evaporation loss rate is 4.8%; The emulsifier is selected from sodium dodecyl benzene sulfonate, the oil agent is selected from mineral oil, the extreme pressure agent is selected from sulfur-phosphorus compound extreme pressure agent, specifically triphenyl phosphite, the anti-rust agent is selected from water-soluble benzotriazole, the preservative is selected from isothiazolinone preservative, specifically methyl isothiazolinone, and the defoaming agent is selected from silicone polyether defoaming agent; Assembling camshaft ultra-deep hole machining system and injecting liquid: the camshaft ultra-deep hole machining system comprises a machine tool 0, a gun drill tool 1, a liquid storage device 4, a temperature control device 5, a high-pressure liquid supply device 6, a chip removal and recovery device 7, a filtration and purification device 8 and a circulating conveying device 9, and each component is connected through a pipeline; wherein the machine tool 0 is selected from an HTT numerical control deep hole drilling machine tool, the gun drill tool 1 is arranged on the machine tool 0 and is slidably connected with the machine tool 0 through a linear sliding assembly, the gun drill tool 1 is driven to rotate and feed by a spindle motor 16 and a feed servo motor (not shown in the figure) respectively, the total length of the gun drill tool 1 is 600 mm, the diameter of the drill rod is 15 mm, the drill rod is internally provided with a liquid supply channel 13 with a diameter of 6 mm, the drill bit is provided with one cutting edge 11, two symmetrical liquid injection holes 12 are arranged on the side of the drill rod at a distance of 10 mm from the drill bit, the angle between the axis of the liquid injection hole 12 and the axis of the drill rod is 30°, and the liquid injection hole 12 is inclined towards the cutting area of the cutting edge 11, and the outer periphery of the gun drill tool 1 is provided with two axial chip removal channels 14. The inner diameter of the through-hole type drill sleeve 2 is 15.2 mm, and the length is 200 mm; the through-hole type drill sleeve 2 is fixed on the machine tool 0 to ensure that the axis thereof is coaxial with the axis of the gun drill tool 1, and the drill sleeve and the gun drill tool 1 form a gap fit of 0.2 mm. The liquid storage device 4 adopts a double-tank design, a first-stage water tank 41 is used to receive the circulating return liquid, and a second-stage water tank 42 is used to store the newly prepared and purified cutting fluid. The temperature control device 5 comprises a water cooler and a temperature sensor, the water cooler is connected with the second-stage water tank 42 through a pipeline, and a temperature sensor with an accuracy of ±0.5℃ is installed in the second-stage water tank 42. The high-pressure liquid supply device 6 comprises a high-pressure flushing pump and a flow meter 15, the high-pressure flushing pump is arranged on the pipeline between the second-stage water tank 42 and the gun drill tool 1, the high-pressure flushing pump needs to ensure that the pressure fluctuation is ≤±0.1 MPa during continuous operation for 24 hours, and the flow meter 15 with an accuracy of ±1% is installed on the liquid inlet pipeline of the gun drill tool 1 to monitor the flow rate in real time. The chip removal and recovery device 7 comprises a water return tank, the water return tank is made of stainless steel, and is arranged directly below the gun drill tool 1 to collect the water-based cutting fluid containing chips flushed during the machining process. The filtration and purification device 8 selects a rubber roller type magnetic separator, the water inlet thereof is connected with the water outlet of the water return tank through a pipeline; the circulating conveying device 9 is an immersion type multi-stage centrifugal pump, the water inlet thereof is connected with the water outlet of the filtration and purification device 8, and the water outlet is connected with the first-stage water tank 41. The above-mentioned components are connected through pressure-resistant pipelines as shown in Figure 1 Then, the prepared water-based cutting fluid stock solution is injected into the second-stage water tank 42.

[0021] Machining process: Clamping the camshaft 3: the camshaft 3 to be machined is firmly clamped on the machine tool 0, so that the end face of the camshaft to be drilled is aligned with the axis of the gun drill tool 1, and the output end of the gun drill tool 1 penetrates through the through-hole type drill sleeve 2 and is aligned with the starting drilling point of the camshaft 3; Cooling water-based cutting fluid: start temperature control device 5, set the target temperature to 8℃, temperature sensor real-time monitoring of the liquid temperature in the secondary water tank 42, when the temperature drops to 8℃, the system automatically maintain constant temperature; High pressure liquid supply: start high pressure liquid supply device 6, set the pressure of high pressure flushing pump to 3.1MPa, flow meter 15 shows the flow rate is stable at 20L / min, matched with the cross-sectional area and pressure of liquid supply channel 13, set the speed of gun drill cutter 1 to 1500r / min, the feed rate is 0.1mm / r; Drilling: start machine tool 0, gun drill cutter 1 starts to rotate and feeds to camshaft 3 with the set feed rate under the drive of main shaft motor 16 and feed servo motor (not shown in the figure), water-based cutting fluid is sprayed at high speed from jet hole 12 to the tiny gap between cutting edge 11 and the hole wall of camshaft 3 through liquid supply channel 13, strong cooling and lubrication are carried out, at the same time, the generated chips are forced out from the chip removal channel 14 on the outer periphery of gun drill cutter 1 by high pressure liquid flow, the chips mixed with water-based cutting fluid fall into the water return tank below, the chip removal speed is 8.8m / s, and the chip removal is smooth; Water-based cutting fluid recycling and regeneration: the water-based cutting fluid containing chips in the water return tank flows into the rubber roller type magnetic separator for filtration, the purified cutting fluid is transported to the primary water tank 41 by the water return pump, the water-based cutting fluid in the primary water tank 41 is transported to the secondary water tank 42 by the immersed multi-stage centrifugal pump, and is mixed with new liquid, every 200 continuous workpieces, the pH value of the water-based cutting fluid in the secondary water tank 42 is detected by the pH meter, when the pH value is ≤7, the antirust agent is supplemented to the system and stirred uniformly until the pH value of the water-based cutting fluid returns to 8.

[0022] Example 2 The difference between this example and example 1 is: When preparing water-based cutting fluid: add 3 parts of emulsifier to 80 parts of water and stir until completely dissolved, and then add 10 parts of oil agent in 4 times under stirring, with an interval of 7 minutes each time, then add 4 parts of extreme pressure agent, 1 part of antirust agent, 1 part of preservative and 1 part of defoaming agent in turn, stir for 15 minutes, and stand for 2 hours; the kinematic viscosity of the water-based cutting fluid under the condition of 40℃ is 10mm² / s, the pH value is 9, and the natural evaporation loss rate is 4.5% in 30 days; wherein the emulsifier is selected from sodium dodecyl benzene sulfonate, the oil agent is selected from mineral oil, the extreme pressure agent is selected from sulfur-phosphorus complex extreme pressure agent, which is composed of sulfur-phosphorus double nitrogen derivative and triphenyl phosphite sulfide according to a mass ratio of 1:1, the antirust agent is selected from water-soluble benzotriazole, the preservative is selected from isothiazolinone preservative, which is composed of methyl isothiazolinone and 5-chloro-2-methyl-isothiazoline-3-ketone according to a mass ratio of 1:1, and the defoaming agent is selected from organosilicon polyether defoaming agent; When assembling the camshaft ultra-deep hole machining system, two symmetrical cutting edges are provided on the drill bit, two symmetrical liquid injection holes are provided on the side surface of the drill rod at a distance of 15 mm from the drill bit, the angle between the axis of the liquid injection hole and the axis of the drill rod is 35°, the inner diameter of the through-hole type drill sleeve is 15.4 mm, and the drill sleeve and the gun drill tool form a clearance fit of 0.4 mm.

[0023] During the machining process: start the temperature control device, set the target temperature to 15℃, when the temperature drops to 15℃, the system automatically maintains constant temperature; start the high-pressure liquid supply device, set the pressure of the high-pressure flushing pump to 3.5MPa, the flowmeter displays that the flow is stable at 25L / min, which matches the cross-sectional area and pressure of the liquid supply channel, set the rotation speed of the gun drill tool to 2000r / min, and the feed amount to 0.15mm / r; the chip removal speed is 9m / s; Except for the above differences, the rest of the process steps and parameters are the same as in Example 1.

[0024] Example 3 The difference between this example and Example 1 is: When preparing the water-based cutting fluid: 4 parts of emulsifier are added to 74 parts of water according to the mass fraction, stirred until completely dissolved, and then 12 parts of oil agent is added in 5 times under stirring, with an interval of 10 minutes each time, and then 5.5 parts of extreme pressure agent, 1.5 parts of rust inhibitor, 1.5 parts of preservative and 1.5 parts of defoaming agent are added in turn and mixed and stirred for 20 minutes, and then left to stand for 3 hours; the kinematic viscosity of the water-based cutting fluid under the condition of 40℃ is 12mm² / s, the pH value is 10, and the natural evaporation loss rate is 4% in 30 days; wherein the emulsifier is selected from sodium dodecyl benzene sulfonate, the oil agent is selected from mineral oil, the extreme pressure agent is selected from sulfur-phosphorus compound extreme pressure agent, specifically triphenyl phosphite, the rust inhibitor is selected from water-soluble benzotriazole, the preservative is selected from isothiazolinone preservative, specifically 5-chloro-2-methyl-isothiazolin-3-one, and the defoaming agent is selected from organosilicon polyether defoaming agent; When assembling the camshaft ultra-deep hole machining system, two symmetrical cutting edges are provided on the drill bit, two symmetrical liquid injection holes are provided on the side surface of the drill rod at a distance of 15 mm from the drill bit, the angle between the axis of the liquid injection hole and the axis of the drill rod is 40°, the inner diameter of the through-hole type drill sleeve is 15.6 mm, and the drill sleeve and the gun drill tool form a clearance fit of 0.6 mm, During the machining process: start the temperature control device, set the target temperature to 25℃, when the temperature drops to 25℃, the system automatically maintains constant temperature; start the high-pressure liquid supply device, set the pressure of the high-pressure flushing pump to 4MPa, the flowmeter displays that the flow is stable at 28L / min, which matches the cross-sectional area and pressure of the liquid supply channel, set the rotation speed of the gun drill tool to 2500r / min, and the feed amount to 0.2mm / r; the chip removal speed is 9.4m / s; Except for the above differences, the rest of the process steps and parameters are the same as in Example 1.

[0025] Comparative Example 1 The difference between this comparative example and Example 2 is that when preparing the water-based cutting fluid, 80 parts of water is increased to 83 parts, and no emulsifier is added, and the remaining process steps and parameters are the same as those of Example 2.

[0026] Comparative Example 2 The difference between this comparative example and Example 2 is that when preparing the water-based cutting fluid, the extreme pressure agent is selected to be triphenyl phosphate, and the remaining process steps and parameters are the same as those of Example 2.

[0027] Comparative Example 3 The difference between this comparative example and Example 2 is that the inner diameter of the through-hole type drill sleeve is 15.1 mm, and the drill sleeve and the gun drill tool form a gap fit of 0.1 mm, and the remaining process steps and parameters are the same as those of Example 2.

[0028] Comparative Example 4 This comparative example uses an oil-based cutting fluid (polyethylene glycol 400 monooleate, model PEG400MO, purchased from Haian Petroleum Chemical Plant in Jiangsu Province) to drill holes in the camshaft.

[0029] The performance of the camshafts and gun drill tools after drilling in Examples 1-3 is tested, and the test results are shown in Table 1.

[0030] Table 1 Performance test of camshafts and gun drill tools after drilling

[0031] As can be seen from the above Table 1, in Examples 1-3, the water-based cutting fluid and the machining process of the present application can successfully machine ultra-deep holes with a depth of 300-700 mm and a length-diameter ratio of up to 30-35 times, and the hole straightness is less than 0.04 mm / m, and the hole surface roughness Ra value is less than 1.2 μm, fully meeting the high precision requirements, and after continuously machining 200 camshafts, the wear of the gun drill tool is less than 180 μm, indicating that the process of the present application can stably achieve high-precision, low-roughness ultra-deep hole machining, and the tool life is good, and the overall performance is better than that of the comparative examples.

[0032] Comparative Example 1 does not add an emulsifier, which causes the hole straightness, surface roughness, and tool wear to be significantly deteriorated, which may be because the lack of emulsifier causes the oily agent and the extreme pressure agent to be unable to be uniformly dispersed in the water, the lubrication and extreme pressure performance of the cutting fluid is sharply decreased, the cutting area cannot be effectively cooled and lubricated, the cutting heat is sharply increased, the friction is intensified, and thus the machining precision is seriously deteriorated and the tool is rapidly worn.

[0033] The extreme pressure agent of Comparative Example 2 is replaced by triphenyl phosphate instead of the sulfur-phosphorus composite extreme pressure agent, which results in poor hole straightness, surface roughness and tool wear. This may be because the reactivity of triphenyl phosphate at high temperature and high pressure and the performance of the generated protective film are not as good as the iron sulfide / iron phosphide composite film generated by the sulfur-phosphorus composite extreme pressure agent of the present application. The iron sulfide / iron phosphide composite film generated by the present application is tougher and has a lower friction coefficient, which can provide more excellent extreme pressure resistance protection, thereby significantly reducing tool wear.

[0034] Comparative Example 3 reduces the clearance fit of the drill sleeve and the gun drill tool from 0.4 mm to 0.1 mm, which results in a sharp deterioration of the machining performance. The hole straightness is as high as 0.31 mm / m, the surface roughness Ra value is as high as 11.3 μm, and the tool wear is as high as 421 μm, which is the worst among all the comparative groups. This may be because the too narrow gap seriously hinders the flow of high-pressure water-based cutting fluid and the smoothness of the chip removal channel. On the one hand, the cutting fluid cannot effectively reach the cutting zone for cooling and lubrication. On the other hand, the chips are easily accumulated and blocked in the narrow gap, forming secondary cutting, which causes uneven stress on the drill, intensifies vibration, and finally causes serious scratches on the hole wall, straightness out-of-tolerance and abnormal tool wear or even breakage.

[0035] Comparative Example 4 uses a traditional oil-based cutting fluid for machining, which has better hole straightness (0.16 mm / m) and surface roughness (2.4 μm) than Comparative Examples 1-3, but still has a significant gap compared with Examples 1-3 of the present application, and its tool wear is similar to that of Example 2, and the overall performance does not show an advantage. This shows that oil-based cutting fluid has certain advantages in lubricity, but the machining quality is poor, and there are high cost and pollution problems. The present application successfully overcomes the inherent shortcomings of water-based cutting fluid in lubricity and chip removal capacity through the careful preparation of high-performance water-based cutting fluid and the optimization of the machining system design, and its machining quality has fully surpassed the traditional oil-based cutting fluid process. At the same time, water-based cutting fluid has great advantages in cost, environmental protection and working environment that oil-based cutting fluid cannot match.

[0036] The above is only an embodiment of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A gun-drilling process for machining ultra-deep holes in camshafts, characterized in that, include: Preparation of water-based cutting fluid: Add 2-4 parts emulsifier to 74-86 parts by weight of water and stir until completely dissolved. While stirring, add 8-12 parts oiliness agent in 3-5 portions, with an interval of 5-10 minutes between each addition. Then, add 2.5-5.5 parts extreme pressure agent, 0.5-1.5 parts rust inhibitor, 0.5-1.5 parts corrosion inhibitor, and 0.5-1.5 parts defoamer in sequence, mix and stir for 10-20 minutes, and let stand for 1-3 hours. The kinematic viscosity of the water-based cutting fluid at 40℃ is 8-12 mm² / s, the pH value is 8-10, and the natural evaporation loss rate after 30 days is ≤5%. Assemble the camshaft deep hole machining system and inject the fluid: The camshaft deep hole machining system includes a machine tool, a gun drill, a fluid storage device, a temperature control device, a high-pressure fluid supply device, a chip removal and recovery device, a filtration and purification device, and a circulation conveying device. The components are connected by pipelines; inject the water-based cutting fluid into the fluid storage device. Cooling the water-based cutting fluid: Activate the temperature control device to cool the water-based cutting fluid to 8-25℃; High-pressure fluid supply and drilling: The high-pressure fluid supply device is activated to deliver the cooled water-based cutting fluid to the gun drill tool at a pressure greater than 3 MPa; the camshaft is drilled through the gun drill tool; the gun drill tool includes a drill rod and a drill bit, the drill bit is provided with at least one cutting edge for drilling the camshaft, the side of the drill rod near the drill bit is provided with at least one spray hole inclined towards the cutting area, the drill rod is provided with a fluid supply channel, the spray hole is connected to the fluid supply channel, during processing, the water-based cutting fluid is sprayed from the spray hole through the fluid supply channel into the gap between the gun drill tool and the camshaft bore wall to cool and lubricate the gun drill tool; the outer periphery of the gun drill tool is provided with an axially extending chip removal channel, under the action of high-pressure fluid flow, the chips are ejected along the gap between the gun drill tool and the camshaft bore wall and enter the chip recovery device along the chip removal channel; Water-based cutting fluid recovery and regeneration: The chip-containing water-based cutting fluid is collected by the chip recovery device and then filtered by the filtration and purification device; the purified water-based cutting fluid is sent back to the storage device by the circulation conveying device for recycling. When the pH value of the recycled water-based cutting fluid is ≤7, the rust inhibitor is added until the pH value of the water-based cutting fluid is restored to 8-10.

2. The gun drilling process for ultra-deep holes in camshafts according to claim 1, characterized in that, In the step of preparing the water-based cutting fluid, the emulsifier is sodium dodecylbenzenesulfonate, the oiliness agent is mineral oil, the extreme pressure agent is a sulfur-phosphorus composite extreme pressure agent, the rust inhibitor is water-soluble benzotriazole, the corrosion inhibitor is isothiazolinone corrosion inhibitor, and the defoamer is an organosilicone polyether defoamer.

3. The gun drilling process for machining ultra-deep holes in camshafts according to claim 1, characterized in that, The gun drill tool is mounted on the machine tool, and the camshaft is clamped on the machine tool and located at the output end of the gun drill tool; The liquid storage device includes a primary water tank and a secondary water tank. The newly prepared water-based cutting fluid is stored in the secondary water tank, and the primary water tank is used to receive the purified water-based cutting fluid for recycling. The temperature control device is connected to the secondary water tank and is equipped with a temperature sensor to monitor the cooling temperature of the water-based cutting fluid. The high-pressure fluid supply device includes a high-pressure flushing pump, which is located on the pipeline between the secondary water tank and the gun drill bit. The high-pressure flushing pump is used to pump the cooled and purified water-based cutting fluid to the gun drill bit. The inlet of the gun drill bit is equipped with a flow meter to monitor the flow rate of the water-based cutting fluid and ensure that the flow rate matches the diameter of the fluid supply channel. The chip removal and recycling device includes a water return tank located below the drill bit, and the outlet of the water return tank is connected to the inlet of the filtration and purification device through a water pipe. The outlet of the filtration and purification device is connected to the primary water tank. The primary water tank and the secondary water tank are connected through the circulation conveying device. The circulation conveying device transports the filtered water-based cutting fluid from the primary water tank to the secondary water tank, thereby realizing the continuous circulation of the water-based cutting fluid within the system.

4. The gun drilling process for machining ultra-deep holes in camshafts according to claim 1, characterized in that, The machine tool is equipped with a through-hole type drill sleeve, which is located between the camshaft and the gun drill tool and has a clearance fit with the gun drill tool. During machining, the gun drill tool passes through the through-hole type drill sleeve and drills the camshaft. The through-hole type drill sleeve is used to guide and support the gun drill tool, prevent the gun drill tool from bending, vibrating or breaking during machining, and ensure the straightness and surface roughness requirements of the drill hole.

5. The gun drilling process for machining ultra-deep holes in camshafts according to claim 1, characterized in that, The circulating conveying device is an immersion multistage centrifugal pump.

6. The gun drilling process for ultra-deep holes in camshafts according to claim 1, characterized in that, The temperature control device includes a water chiller.

7. The gun drilling process for ultra-deep holes in camshafts according to claim 1, characterized in that, The filtration and purification device is a roller-type magnetic separator.

8. The gun drilling process for machining ultra-deep holes in camshafts according to claim 1, characterized in that, The output pressure of the high-pressure flushing pump must be controlled above 3MPa, and the pressure fluctuation must be ≤±0.1MPa for continuous operation for 24 hours. The chip discharge velocity must be ≥8.8m / s.

9. The gun drilling process for machining ultra-deep holes in camshafts according to claim 1, characterized in that, The gun drill bit has a rotational speed of 1500-2500 r / min and a feed rate of 0.1-0.2 mm / r.

10. The gun drilling process for machining ultra-deep holes in camshafts according to claim 1, characterized in that, The ultra-deep hole has a depth of 300-700mm, a diameter of 10-20mm, an aspect ratio of 30-35, a straightness of <0.04mm / m, and a surface roughness Ra value of <1.2μm.

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