Research on the influencing factors of chip forming in 304 stainless steel deep hole gun drilling

doi:10.21203/rs.3.rs-3596193/v1

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Research Article

Research on the influencing factors of chip forming in 304 stainless steel deep hole gun drilling

https://doi.org/10.21203/rs.3.rs-3596193/v1

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published 05 Aug, 2024

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In deep hole gun drilling, the relationship between process parameters and chip forming process has always been a difficult point in the research of deep hole machining because of the small hole diameter, long hole depth, and narrow chip removal space.304 stainless steel has good corrosion and heat resistance and is widely used in medical treatment, food processing, and other fields. However, it also has processing difficulties, such as high hardness and poor plasticity. Therefore, this paper takes 304 stainless steel as the research object, with the help of Abaqus simulation software, simulates the chip forming process in the process of deep hole gun drilling and studies the influence of process parameters on chip forming. According to the simulation results, based on the fluid-solid coupling theory, the fluid-solid coupling simulation model is established through Ansys-Fluent simulation software. The influence of coolant pressure on chip forming is studied, and the relationship between coolant pressure and chip curling deformation is expounded in different growth periods of chips. Then, the deep hole gun drilling test was carried out, and the chip morphology was analyzed. Finally, the paper revealed the relationship between chip forming and process parameters in deep-hole gun drilling.

gun drill processing

304 stainless steel

chip forming

fluid-solid coupling

In the mechanical manufacturing industry, about one-third of the entire hole processing demand relates to deep hole processing. The demand for small diameter long deep holes is increasing in national key development industries such as aerospace, weaponry, automobiles, and the energy chemical industry. Gun drilling is a crucial technical method for achieving deep-hole processing. Gun drilling consists of a drill bit, pipe, and stem. Typically, manufacturers use cemented carbide material for the drill bit and roll steel pipe to create the drill pipe. The drill bit and drill pipe are welded together. Figure 1 illustrates the overall structure of gun drilling.

Researchers mainly focus on studying the processing of specific materials in gun drill processing, such as titanium alloy, 45 steel, stainless steel, and other difficult-to-machine materials. Among these materials, 304 stainless steel is particularly noteworthy due to its excellent corrosion resistance, heat resistance, low-temperature strength, and mechanical properties. It finds widespread use in industries like automotive parts and medical equipment[1]. However, 304 stainless steel parts are considered plastic materials, which can lead to challenges in the processing process, such as chip blockage and tool sticking[2], resulting in poor processing quality. Scholars in the industry have been addressing this scientific issue for some time. Here is a summary of domestic and foreign scholars' research on chip formation and processing quality: Biermann et al. utilized a high-speed camera to record the chip formation process, and they identified significant differences in the chip formation process for various materials during drilling [3–4]. Yingjian Tian et al. investigated the impact of process parameters on chip formation and processing quality to address issues like difficult chip breakage and poor surface quality during conventional drilling[5]. They found lower rotational speed and appropriate feed rates improved chip formation and surface quality. Pawade et al. studied the effect of chip deformation on the processing quality of Inconel-718 and determined that favorable chip morphology significantly influenced improving processing quality[6]. Wang Yongguo et al. analyzed chip morphology and tribological mechanisms under different cutting conditions, revealing the wear mechanisms of TiAIN-coated gun drills. They discovered that chip morphology could reflect the wear process, changing chip shape during different wear stages[7]. Xie et al. studied the influence of changes in the gun drill's inner and outer edge angles on chip formation and processing quality, determining the angles of the inner and outer cutting edges suitable for processing 304 stainless steel[8].

In summary, these studies have been conducted through experimental analysis of the chip formation process without theoretical analysis of chip curling deformation. Additionally, most of these studies did not consider the impact of coolant on chip curling deformation. Therefore, this paper aims to analyze the influence of process parameters on chip formation for 304 stainless steel materials using Abaqus simulation software. The paper constructs a fluid-solid coupling simulation model to investigate the relationship between oil pressure and the degree of chip curling. The paper conducted a deep hole gun drilling experiment to collect chips for further analysis.

Gun drilling is a typical double-edged cutting, and both the drill's inner and outer cutting edges are involved in the processing. When the inner edge contacts and rotates with the surface of the workpiece, the metal inside the workpiece will be cut to form a finer chip. When the outer edge contacts and rotates with the outer wall of the workpiece, the outer wall will be cut to produce a wider and thinner chip. In addition, the cutting speed of the outer edge is greater than that of the inner edge, which will produce extrusion creases at the junction of the inner and outer edges. According to the research of Li Liang et al. the chip forming process during deep hole gun drilling can be divided into four stages: lateral curling stage, spiral initiation stage, spiral chip forming stage, and chip fracture separation stage. Figure 2 is a schematic diagram of the chip-forming process[9–11].

1) Chip lateral curling stage

In the early stage of deep hole gun drilling, when the tool contacts the surface of the workpiece, the inner and outer edges of the drill begin to cut metal materials. At this stage, the cutting edge applies the cutting force to the workpiece, and the metal starts to cut, but the chip has not yet completely separated from the surface of the workpiece. Due to the ductility of the metal, the chip will curl laterally along the surface of the workpiece. Figure 3 is the chip lateral curling stage.

2) Spiral initial stage

As shown in Fig. 4, under the action of feed and rotation of the drill bit, the inner and outer cutting edges participate in the processing simultaneously, and the chips begin to form. When the feed reaches a certain depth, the chips first contact the V-groove wall surface, and the chips begin to be subjected to the resistance applied by the V-groove wall surface. Due to the design and shape of the V-groove, it will guide the chips to curl up along the wall surface. When the chip is in contact with the hole wall, the chip is subjected to the friction force between the chip and the hole wall and the axial force applied by the drill bit, and the second upward curl begins to occur.

3) Spiral chip forming stage

The chip length increases as the gun drill deepens, and the chip gradually becomes a spiral shape. Before the final fracture of the chip, multiple spiral curl cycles can be formed. The chips will continue to curl, fall off, and re-form from the workpiece until the chips reach a certain length, encounter obstacles, and finally break. As shown in Fig. 5, the spiral chip formation stage, in this stage, the chip is subjected to the resultant force F_w applied by the hole wall and the resistance F_v applied by the V-groove so that the spiral chip begins to form, V_f is the generation speed of the chip in the feed direction, and V_cf is the generation speed of the spiral chip.

In addition, the degree of chip curling will be affected by the coolant force F_l. Figure 6 shows the effect of coolant on the chip curling radius. In the absence of coolant supply, the curl radius of the chip is R_c1; under the action of coolant, the chip curls and deforms, and the curl radius increases to R_C2.

4) Chip fracture separation stage

304 stainless steel is a typical difficult-to-machine material, and the fracture mechanism is very complex. The cutting speed of the inner and outer edges of the gun drill is different, and the cutting temperature is also different, resulting in different fracture mechanisms. The cutting speed of the inner edge is smaller than that of the outer edge, and the cutting temperature is lower. There are more 'river patterns 'on the chip fracture, mainly brittle fracture. The high temperature generated during the cutting of the outer edge leads to the softening of the workpiece, and the chips are primarily ductile fractures.

According to the theoretical analysis of the chip forming process, it can be concluded that the chip forming in the process of the gun drill is closely related to the angle of the inner and outer edges of the gun drill bit, the material of the workpiece, the processing parameters and the pressure of the coolant.

The process parameters have an important influence on the chip forming. The selection of these parameters will affect the chip shape and size, chip removal, and the stability of the drilling process. This paper uses a standard angle gun drill for 304 stainless steel materials. With the help of Abaqus software, different spindle speeds, and feed rates are selected for drilling simulation. The chip-forming process is studied, and the chip curling radius is measured. The influence of spindle speed and feed rate on chip curling deformation is studied.

3.1 Establish drilling simulation model

The drill bit material used in this paper is cemented carbide, the brand is YG8, and the specification is Φ17 * 50mm. The material of the workpiece is 304 stainless steel with a diameter of 28 mm. In this paper, to improve the mesh quality and reduce the computational cost, the geometric structure of the gun drill is simplified, and the drill's size parameters and geometric angle are retained. At the same time, the workpiece is processed accordingly. Corresponding to the geometric angle of the drill bit, the simplified drill bit simulation model in this paper will not have a huge impact on the simulation results. Figure 7 is the three-dimensional drilling finite element simulation geometric model.

3.2 Material model

The material model is the decisive condition to ensure the validity of finite element analysis[12]. In this paper, the Johnson-Cook constitutive model suitable for large deformation is selected, and its expression is as follows.

$$\stackrel{-}{\sigma }=\left[A+B{\left({\stackrel{-}{\epsilon }}^{pl}\right)}^{n}\right]\left[1+C\text{l}\text{n}\frac{\dot{{\epsilon }}}{{\dot{{\epsilon }}}_{0}}\right]\left[1-{\left(\frac{T-{T}_{\text{0 }}}{{T}_{\text{m}}-{T}_{\text{0 }}}\right)}^{m}\right]$$

In the formula: A is yield strength, B and n are strain hardening parameters, ε is the reference strain rate, C is the strain rate coefficient, T₀ is room temperature, 20 degrees Celsius, T_m is the melting point of the material, m is the thermal softening parameter. Table 1 shows the Johnson-Cook model parameters of 304 stainless steel.

Table 1

Johnson-Cook model parameters of 304 stainless steel[13]
A(MPa)	B(MPa)	n	C	m	${\text{T}}_{\text{melt}}$(℃)	$\text{T}$0(℃)
454	1962	0.752	0.1732	0.699	1400	20

3.3 Boundary condition setting

In this paper, in the setting of boundary conditions, the drill bit is set as a rigid body, the workpiece is set as a plastic body, and the heat transfer analysis is turned on to fix the workpiece to prevent the workpiece from moving during the drilling process. The drill bit sets the corresponding speed and feed. This paper has two drilling parameters: spindle speed and feed rate. Seven simulation experiments are designed to use these two processing parameters as variables. The simulation parameters are shown in Table 2.

Table 2

Simulation processing parameter table
No.	Hole diameter (mm)	Hole depth (mm)	spindle speed(r/min)	Feed rate (mm/r)
1	17	30	1200	0.01
2	17	30	1200	0.02
3	17	30	1200	0.03
4	17	30	1200	0.04
5	17	30	900	0.02
6	17	30	1500	0.02
7	17	30	1800	0.02

3.4 Model solving

The paper used Abaqus / Explicit to calculate the model. After the calculation, enter the Abaqus post-processing module to analyze the chip-forming process. Figure 8 shows the forming process of the chip under the speed of 1200 r / min and the feed rate of 0.02 mm / r. In the initial stage of gun drilling, the inner and outer edges of the drill bit first contact the workpiece, and the chip is curled laterally. As the processing continues, the chip contacts the V-groove wall and begins to curl upward, and the spiral chip begins to produce and finally breaks.

3.5 Analysis of simulation results

In deep hole gun drilling, the chip curling radius theoretical model is usually relatively complex and is affected by many parameters, including spindle speed, feed rate, material properties, cutting fluid, tool geometry, etc. This paper measures the curl radius of chips under different process parameters simultaneously, as shown in Fig. 9, and the detailed data are shown in Table 3.

Table 3

Chip curl radius
No.	spindle speed (r/min)	Feed rate (mm/r)	curl radius (mm)
1	1200	0.01	4.45
2	1200	0.02	4.47
3	1200	0.03	5.09
4	1200	0.04	5.38
5	900	0.02	4.43
6	1500	0.02	6.17
7	1800	0.02	6.99

Figure 10 shows the change curve between the chip curling radius and the processing parameters. It can be concluded that the chip curling radius is positively correlated with the feed rate and the spindle speed. As the feed rate and the spindle speed increase, the chip curling radius gradually increases, the chip curvature decreases, and the chip is more curved.

When the spindle speed is 1200r / min and the feed rate is 0.01mm / r, the chip curling radius is 4.45mm. When the feed rate increases to 0.02mm / r, the chip curling radius is 4.77mm, and the increment of the curling radius is 7.19%. When the feed rate increases to 0.03 and 0.04 mm / r, the curl radius is 5.09 mm and 5.38 mm, respectively, and the increment of curl radius is 6.7% and 5.69%, respectively. Therefore, increasing the feed rate, the curling radius of the chip will become larger, and the increase of the feed rate will also lead to an increase in the chip thickness; the ability of the chip to resist bending deformation will increase, increasing the curling radius of the chip.

Under the processing parameters of 0.02mm / r feed rate, when the spindle speed is 900r / min, the curling radius of the chip is 4.43mm. When the spindle speed increases to 1200r / min, the curling radius of the chip is 5.22mm, and the increment of the curling radius of the chip is 17.83%. When the spindle speed increases to 1500r / min and 1800r / min, the curling radius is 6.17mm and 6.99mm, respectively, and the increment of the curling radius is 16.19% and 13.3%, respectively. Therefore, the chip's curling radius increases with the feed rate increase. When the spindle speed increases to a certain extent, the increment of the chip curling radius decreases.

In deep hole gun drilling, the influence of spindle speed on-chip curling degree is greater than that of feed rate on chip curling degree. This phenomenon is because the spindle speed mainly affects the cutting speed. Higher cutting speed makes it easy to produce longer chips, making the chips' curling radius larger. The increase in the feed rate will lead to an increase in the cutting force applied to the drill bit during the cutting process. The size and direction of these cutting forces will affect the formation and curl of the chip during the cutting process. The feed rate also affects the chip thickness. As the feed rate increases, the chip thickness increases, and the ability of the chip to resist deformation increases, resulting in a decrease in the increment of the chip curl radius.

In the process of deep hole gun drilling, the cutting fluid not only plays a role in cooling and lubrication but also has an important influence on the degree of chip curling, chip breaking, and flow process. Therefore, based on the chip forming theory and the simulation results in the third section, this paper establishes a simulation model of coolant flow field-chip fluid-solid coupling and analyzes the flow path of coolant and the pressure distribution and pressure loss near the drill edge under different coolant pressures. The influence of coolant on the degree of chip deformation in different stages of chip forming is analyzed, which guides the selection of coolant pressure in the process of deep hole gun drilling.

4.1 Fluid-solid coupling simulation model simplification and meshing

This paper focuses on the chip deformation near the cutting edge of the drill bit. The drill bit and fluid area are simplified to reduce the amount of simulation calculation and shorten the calculation time. Figure 12 is the flow chart of the fluid-solid coupling simulation, and Fig. 13 is the fluid-solid coupling simulation model.

In this paper, hexahedral mesh is used. The chip surface is used as the fluid-solid coupling interface to study the degree of chip curling deformation. Therefore, it is necessary to encrypt the mesh near the chip. The first wall layer is set to 0.005 mm, and the mesh quality is optimized. The number of mesh divisions is 2.7 million, and the mesh division is shown in the figure.

4.2 Determination of boundary conditions and simulation parameters

The CFD numerical simulation in this section takes the coolant inlet pressure as a single factor variable. Therefore, after the grid is imported into Fluent, the pressure basis is selected to solve the turbulence model k-ω-SST. In this paper, the initial value of the inlet pressure is 2.5Mpa, with each increase of 0.5Mpa, increased to 5Mpa, the outlet pressure is 0, the simulation experiment, the specific simulation parameters are as follows.

Table 4

Boundary condition setting
Item	Setting
Solution module	Workbench-Fluent
Turbulence model	k-ω-SST
Fluid domain material properties	Density: 998.2 kg/m³ Viscosity: 4 Pa.s
Boundary condition	Pressure-inlet:2.5Mpa∼5Mpa Pressure outlet: 0 Spindle speed: 1200r/min

4.3 Coolant flow field simulation results analysis

Figure 15 shows the streamline distribution near the drill bit. The flow of deep hole gun drilling cutting fluid belongs to the complex finite space rotating turbulent jet. A rotating jet will form when the cutting fluid is ejected from the oil hole. After the pressure loss is generated by the jet flowing through the net surface area of the bottom gap, a turbulent rotating jet will be formed again and enter the V-groove.

When the coolant flows to the bottom of the drill bit, it will generate pressure on the cutting edge and the chip. Figure 16 is the pressure distribution cloud diagram of the rake face and the flank face under different coolant pressures. By analyzing the pressure cloud diagram, it can be concluded that in the process of deep hole drilling, the coolant will generate pressure on the rake face and the flank face of the drill bit. Due to the structural design of the drill bit, a high-pressure zone and low-pressure zone will be generated near the inner and outer cutting edges. The high-pressure zone is mainly distributed on the outer cutting edge, and the low-pressure zone is distributed near the inner cutting edge. Under pressure difference, the chip curls from the high-pressure zone to the low-pressure zone.

Figure 17 shows the relationship curve between the outlet pressure, the inlet pressure, and the pressure loss rate. When the coolant flows from the inlet to the outlet, it will be accompanied by pressure loss, and when the coolant pressure is small, the pressure loss is large. When the inlet pressure is 2.5Mpa, the maximum outlet pressure is 2.09Mpa, and the pressure loss rate is 16.4%. When the inlet pressure is 3Mpa, the maximum outlet pressure is 2.76Mpa, and the pressure loss rate is 8%. In increasing the inlet pressure from 3.5Mpa to 5Mpa, the pressure acting on the cutting edge also gradually increases, and the high-pressure zone gradually diffuses to the inward cutting edge. The maximum pressure is 3.45Mpa, 3.98Mpa, 4.42Mpa, 4.86Mpa, and the pressure loss are 1.4%, 0.5%, 1.7% and 2.8%, respectively.

4.4 Analysis of the influence of coolant on chip curling degree

The coolant will affect the curl deformation of the chip. In this paper, the inlet coolant pressure is used as a variable to study the effect of coolant pressure on the curl deformation of the chip at different growth stages.

Fig.18 shows the effect of coolant on chip curling deformation in the chip lateral curling stage. According to the simulation, it is found that in the early stage of chip growth, under the action of coolant, the chip appears to have a ' cantilever beam ' bending deformation. When the coolant pressure is 2.5Mpa, the maximum deformation of the outer edge of the chip top is 0.33mm. In the process of increasing the oil pressure from 3Mpa to 5Mpa, the maximum deformation of the chip caused by the coolant is 0.39mm, 0.46mm, 0.48mm, 0.52mm, and 0.56mm. The degree of chip curl deformation increases with the increase of coolant pressure.

Figure 19 shows the effect of coolant on chip curling deformation in the spiral initiation stage. When the coolant pressure is 2.5Mpa, the maximum deformation of the outer edge of the chip top is 0.61mm; in the process of increasing the oil pressure from 2.5Mpa to 5Mpa, the maximum deformation of the chip caused by the coolant is 0.78mm, 0.95mm, 1.03mm, 1.11mm, and 1.27mm respectively.

Figure 20 shows the influence of coolant on the degree of chip deformation in the spiral chip-forming stage. The chip length in this stage is longer, and the influence of coolant on the degree of chip deformation is much greater than that in the first two stages. When the coolant pressure is 2.5Mpa, the maximum deformation of the chip is 1.22mm. In the process of increasing the coolant pressure from 2.5Mpa to 5Mpa, the maximum deformation of the chip caused by the coolant is 1.35mm, 1.46mm, 1.66mm, 1.71mm, and 1.75mm, respectively.

Figure 21 shows the influence of coolant on chip curling deformation at different growth stages of chips. By analyzing the curve, it can be concluded that coolant will affect the forming process of chips. Whether in the lateral curling stage, the spiral initiation stage, or the spiral chip forming stage, the maximum deformation of chips always occurs at the outer edge of chips, and the deformation increases with the increase of coolant pressure. In the lateral curling stage of the chip, due to the short length and small shape, the coolant has little effect on the curling deformation of the chip; when the coolant pressure increases to 5Mpa, the maximum deformation is still below 0.6mm. In the initial spiral curling stage, the chip length increases, and the stress area rises, increasing the degree of curling deformation of the chip; when the pressure reaches 5Mpa, the maximum deformation can reach 1.2mm. In the spiral chip forming stage, the chip length increases continuously, and the coolant has the most apparent scouring effect on the chip; when the coolant pressure is 5Mpa, the maximum deformation of the chip is 1.75mm. In addition, no matter at which stage, when the coolant pressure increases to 4Mpa, the trend of chip curl deformation slows down.

In the fourth section of this paper, the deep hole gun drilling experiment is carried out using a drilling machine tool, the chips produced in the drilling process are collected, and the influence of process parameters on chip forming is analyzed.

5.1 Test Equipment and Installation

The drilling machine used in this paper is the NCS1600 CNC machine tool. The machine tool draws on the processing experience of foreign machine tools and combines the actual processing needs of domestic industries to design and manufacture processing equipment. The CNC drilling machine is shown below.

The tool used in this paper is a 17 mm standard single-edged gun drill. The 304 stainless steel cylindrical bar with a diameter of 28 mm and a length of 1000 mm is used, and a guide sleeve with a diameter of 17.02 mm is clamped at the head of the drill to guide. The installation and positioning methods of the workpiece and the gun drill are as follows.

5.2 Machining parameters table

In this paper, to reduce the interference of other factors on the drilling test of gun drilling, the same 304 stainless steel bar is used for processing during the experiment. The bar specification used in the gun drilling test is Φ28 * 1000mm. After the processing is completed, the drilling chips are collected. Table 5 is the processing parameter table of the deep hole gun drilling test.

Table 5

machining parameters table
No.	Hole diameter (mm)		Feed rate (mm/r)	Coolant pressure (Mpa)
1	17	1200	0.01	3.5
2	17	1200	0.02	3.5
3	17	1200	0.03	3.5
4	17	1200	0.04	3.5
5	17	1200	0.02	2.5
6	17	1200	0.02	3.0
7	17	1200	0.02	4.0

5.3 Chip morphology analysis

Process parameters have a certain influence on chip forming. Usually, appropriate processing parameters can help control the shape and size of chips, thereby improving processing quality and efficiency.

Fig.24 shows the influence of feed rate on chip forming under the coolant pressure of 3.5Mpa. When the feed rate is 0.01mm / r, the chip thickness is thin, the inner and outer edge extrusion marks are not obvious, the outer edge chip is the main chip, and the chip is the unit chip. When the feed rate increases to 0.02 mm / r, the chip thickness increases, and spiral chips appear. When the feed rate increases, the chip thickness increases, and the chip length gradually increases.

Figure 25 shows the influence of coolant on chip morphology. The pressure of the coolant will not only affect the curling degree of chips but also affect the chip-breaking process. As the coolant pressure increases, the chip-breaking effect increases, and the chip length decreases. When the coolant pressure is 2.5Mpa, the chip length is 97mm; when the coolant pressure increases to 3Mpa, the chip-breaking effect of the coolant is obvious, and the chip length is 48mm. When the coolant pressure continues to increase, the chip length continues to decrease, in turn, to 38mm and 24mm.

(1) In this paper, the chip-forming process in the process of deep hole gun drilling is analyzed. The chip forming process can be divided into lateral curling stage, spiral initial stage, spiral chip forming stage, and chip fracture separation stage. Moreover, the process parameters have an important influence on chip forming. Therefore, the chip-forming process can be optimized by changing the processing parameters, thereby improving the processing quality of the gun drill.

(2) In this paper, Abaqus simulation software is used to simulate the chip-forming process for 304 stainless steel material and a 17 mm deep hole gun drill. The curl radius of chips under different process parameters is measured, and the relationship between the curl radius of chips and process parameters is obtained: the curl radius of chips increases with the increase of spindle speed and feed rate; the influence of spindle speed on chip-forming is greater than that of feed rate on chip-forming.

(3) Based on the fluid-solid coupling theory, the fluid-solid coupling model is established, and the deep hole gun drilling experiment is carried out. The pressure distribution of the rake face and the flank face, the pressure loss rate of the coolant, and the influence of the coolant on the chip curling deformation are studied. It can be concluded that there is pressure loss in the process of coolant flowing into the drill bit, and the pressure loss decreases with the increase of inlet pressure. When the inlet pressure is 2.5Mpa, the pressure of the rake face is 2.09Mpa, and the pressure loss rate is 16.4%. When the inlet pressure increases to 5Mpa, the pressure on the rake face is 4.86Mpa, and the pressure loss tends to be stable at only 2.8%. In addition, the coolant also affects the degree of chip deformation. At different stages of chip forming, the coolant has different effects on chip curling deformation: the effect is the smallest in the lateral curling stage and the greatest in the spiral chip forming stage.

a. Funding (the Natural Science Research of Jiangsu Higher Education Institutions of China (20KJA460005), Jiangsu Postgraduate Innovation Program (SJCX22_1678), Yancheng Key Research & Development (industrial support) Program (BE2023028))

b. Conflicts of interest/Competing interests (Not applicable)

c. Availability of data and material (Not applicable)

d. Code availability (Not applicable)

e. Ethics approval (Not applicable)

f. Consent to participate (Not applicable)

g. Consent for publication (Not applicable)

h. Authors' contributions (Not applicable)

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Research on the influencing factors of chip forming in 304 stainless steel deep hole gun drilling

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Journal Publication

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Abstract

Figures

1 Introduction

2 Analysis of 304 stainless steel chip forming process

1) Chip lateral curling stage

2) Spiral initial stage

3) Spiral chip forming stage

4) Chip fracture separation stage

3 The influence of process parameters on chip forming

3.1 Establish drilling simulation model

3.2 Material model

3.3 Boundary condition setting

3.4 Model solving

3.5 Analysis of simulation results

4 Effect of coolant pressure on chip curling deformation

4.1 Fluid-solid coupling simulation model simplification and meshing

4.2 Determination of boundary conditions and simulation parameters

4.3 Coolant flow field simulation results analysis

4.4 Analysis of the influence of coolant on chip curling degree

5 Experimental study on gun drill processing

5.1 Test Equipment and Installation

5.2 Machining parameters table

5.3 Chip morphology analysis

6 Conclusion

Declarations

References

Status:

Journal Publication

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