Method and apparatus for coordinating energy on a workpiece processing zone

Abstract

The invention relates to machining workpieces. In the invention, a pair of workpiece and tool materials are selected and the workpiece material is machined using the tool. Simultaneous with the machining, there is a step of providing an external, electrically charged gaseous medium to the work zone, workpiece and tool contacts. The resulting charged polarity of the gaseous medium depends on the selected pair of workpiece and tool materials to coordinate their resulting internal thermal energy and charge, enthalpy levels and electrochemical reactions in the work zone, workpiece and tool during machining.

Description

Technical Field

[0001] This invention relates to the machining of workpieces. In particular, this invention relates to the coordination of energy in the workpiece machining area. Background Technology

[0002] The modern goal of metal cutting processes is to increase productivity for a variety of machining operations. The only feasible option is to increase productivity by increasing cutting speed. However, it is known that this increase in cutting speed results in increased cutting temperature and tool wear, among other critical characteristics.

[0003] Today, metal cutting faces several new challenges: a) the increasing use of specialty alloys with advanced properties and significantly higher quality requirements for machined parts; b) intensifying global competition; and c) environmental requirements for ecological improvement. Therefore, the global metal cutting industry needs new solutions.

[0004] US 5551324 discloses a method and apparatus for cooling a machining zone using an ionized gaseous fluid. GB2243319 and RU 2004122051 disclose a cutting device in which the airflow is ionized. EP 1875994 discloses a machining tool that can be used in the woodworking industry. This tool utilizes an ionized airflow. Summary of the Invention

[0005] The objective of this invention is to provide an alternative method for machining workpieces. This objective is achieved by means of the independent claims. The dependent claims describe different embodiments of the invention.

[0006] An inventive method for machining workpiece material includes the steps of selecting a pair of workpiece and tool materials and machining the workpiece material using the tool. Simultaneously with machining, there is a step of providing an external, charged gaseous medium to the working area, workpiece, and tool contacts. The charged polarity of the gaseous medium depends on the selected pair of workpiece and tool materials to coordinate the internal heat energy and charge, enthalpy level, and electrochemical reactions generated in the working area, workpiece, and tool during machining. Attached Figure Description

[0007] The invention is described in detail below with reference to the accompanying drawings, wherein,

[0008] Figure 1 The diagram illustrates the sources of heat generation.

[0009] Figure 2 The diagram illustrates the principle of the electromotive force method.

[0010] Figure 3 and Figure 4 The diagram illustrates the basic configuration of the work area, in which a gaseous medium permeates all zones.

[0011] Figure 5 of (a), Figure 5 (b) Figure 5 (c) illustrates the different neutralization mechanisms.

[0012] Figure 6 An example of neutralization current is illustrated.

[0013] Figure 7 The figure illustrates an example of average ion density versus input pressure.

[0014] Figure 8 The figure shows the temperature under different set pressures.

[0015] Figure 9 The illustration shows examples of test results for a carbon steel cutting test setup under different cutting speeds, and...

[0016] Figures 10 to 14 The diagram illustrates the results of different cutting tests. Detailed Implementation

[0017] For decades, many different theories and models have been used to study the most well-known correlation between cutting speed, heat generation, and tool life. The generated heat and its distribution are among the main topics, creating temperature fields in the workpiece, chips, and tool. Heat generation has three sources: I. the shear and deformation zone, where the cut layer gradually transforms into chips; II. the tool-chip interface, where chips slide on the tool rake face; and III. the tool-workpiece interface, where the machined surface slides over a small area on the tool flank face. These sources are schematically illustrated in… Figure 1 As shown in the image.

[0018] The strongest heat generation occurs in the shear / deformation zone, accounting for 65%-90%, and 10%-35% of the heat is generated by friction at the tool-chip and tool-workpiece interfaces. In the machining of various steels, approximately 75%-90% of the total heat is generated by plastic deformation. However, the highest temperature is typically reached at the tool-chip interface, and the temperature in front of the fractured cutting edge is reduced by thermal adsorption.

[0019] The achieved temperature (thermal energy, the balance between exothermic and endothermic processes) can be characterized, for example, by an electromotive force (EMF). Different methods and theories exist, such as the Seebeck EMF caused by a junction of dissimilar metals, the Peltier EMF caused by current flow in a circuit, and the Thomson EMF caused by a temperature gradient in the connected materials. The Seebeck EMF depends on the junction temperature, which is known for any junction formed from most common metals, and therefore, junctions of dissimilar metals can be used to measure temperature if the resulting EMF is carefully measured. Table 1 shows the thermoelectric potentials of some commonly used materials.

[0020]

[0021]

[0022] Note that the reference junction is at 0°C and the terminal junction is at 100°C.

[0023] Table 1

[0024] The table presents the thermoelectric potentials of some commonly used metals and alloys, along with platinum, in millivolts.

[0025] Figure 2 The principle of the electromotive force method is illustrated. Because the tool and workpiece materials are normally different, their contacts at the tool-chip and tool-workpiece interfaces form a thermal junction of a tool-workpiece thermocouple. The thermocouple component is insulated from the machine and fixture to eliminate noise in the output signal. This output signal, an electromotive force voltage, is amplified and then fed into a data acquisition board plugged into a computer for further analysis.

[0026] Machining is based on many technologies. However, materials-related atoms, molecules, and ions are always involved, with electromechanical, triboelectric, and electrochemical processes between the workpiece and tool actively participating. During machining, especially in metal cutting, the workpiece is typically losing electrons. At the atomic level, cutting the workpiece causes an electrical process, in which valence electrons leave the atoms of the workpiece material as the cutting tool propels forward, creating charged regions within the workpiece that weaken its strength and ultimately cause it to be removed as cutting chips. This type of process occurs in the deformation zone, where most of the heat energy is generated. Atoms are losing electrons near the tool and forming positive potentials (cations), which requires specific ionization energy levels necessary to charge the material. This charging process is crucial in material cutting, and the resulting repulsive forces between ions in the workpiece cause them to be removed from the workpiece material. Specific ionization energy levels have been characterized in different materials. Therefore, this region of the deformation zone can be called the ionization zone.

[0027] This ionization process is crucial in metal cutting to sustain this repetitive charging. The required ionization energy level depends on the pair of materials, workpiece, and tool used, which primarily define the required ionization energy and the forces that remove or add electrons to atoms. In the case of metal cutting, atoms are typically losing electrons. Depending on the electrochemical process, it can be exothermic or endothermic, where thermal energy is released or absorbed.

[0028] The necessary condition for an electrochemical reaction is the collision of the reactant atoms, molecules, and ions with the material surface. When cutting metal, the atoms, molecules, and ions are in a gas-like state, and the metal surface is in an elasto-plastic phase, making electrochemically active reactions possible. The smaller the difference between the levels of direct and reverse electrochemical reactions, the less energy is required for activation (ionization energy). Therefore, it is important to optimize the balance of the electrochemical reaction (i.e., the balance between exothermic and endothermic reactions) to minimize the required activation energy, which directly affects cutting force, heat distribution, elasticity, and plastic deformation.

[0029] A rapidly changing potential arises on the contact surface between the workpiece and the tool. Therefore, the aforementioned thermocouple phenomenon can be divided into two components: a constant and a variable. The constant component depends on the thermoelectric tension, while the variable component characterizes the thermoelectric processes arising from the contacting surfaces with friction. The thermoelectric current is greater than the thermionic current, and for this reason, the thermoelectric current is often used when measuring the average temperature of the cutting tool edge (refer to Seebeck), and research on the thermionic current is relatively limited. Some existing solutions utilize an external power source by feeding a voltage level onto the tool insert and creating a polarity effect in the cutting zone. This solution has some impact on machining. However, this approach is unsuitable for use in practical industrial machinery because the challenges of powering industrial machinery result in significant and disturbing electrical interference. Another approach utilizing ionized air in metal cutting has also been presented, with basic experiments presented. However, the crucial facts regarding polarity and the chosen workpiece and tool materials are not disclosed; these are core issues concerning the thermionic current, internal charge control, neutralization, and ionic bonding. Therefore, a lack of understanding provides reliable functional methods for controlling and optimizing the electromechanical and electrochemical reactions involved in machining.

[0030] Based on the above description of activation energy and internal charges (thermoelectrics, thermoelectrics, etc.) in machining and cutting, and the challenges of increasing machining speeds using common metalworking fluids, this invention can provide a new level of machining results. This electromechanical and electrochemical invention is based on a method of coordinating the activation energy of material machining and cutting with the internal charges on the contact surfaces and the triboelectric energy on the material surfaces, so as to minimize the generated internal heat, enthalpy level, cutting force, and tool wear as cutting speeds increase and surface roughness improves. This coordination method is based on the generated and optimized external charged gas medium (flux) to the working area, workpiece, and tool contact points, wherein the polarity of the formed gas medium depends on the selected pair of workpiece and tool materials to coordinate the internal heat and charge, enthalpy level, and electrochemical reactions generated during machining. The charged gas medium is a flow of ionization flux in which ions based on anions or cations are generated to simultaneously combine and coordinate the charge and electrochemical reactions of the materials in the working area. The selected pair of materials needs to have an optimized gas medium (flux) to coordinate the cation and anodic polarities and enthalpy levels in the working area. The gaseous medium can be based on an ionized air flux with more anions or cations or combinations thereof, thus exhibiting positive, negative, or bipolar polarity, depending on the selected pair of workpiece and tool materials. Furthermore, depending on the selected pair of workpiece and tool materials, other gaseous media, such as argon, nitrogen, or others, can be utilized to achieve a preferred ionic charge for work area coordination. By using the ionized medium, the required ionization energy is minimized.

[0031] This invention is also applicable to conductive, metallic, insulating, coated, and even non-conductive, non-metallic materials, where high electrostatic charge is involved and can be harmonized by ion neutralization and / or recombination. The charged gaseous medium can permeate all working areas and all surfaces, including tools, thereby influencing surface energy, electronic and atomic repulsion, surface oxidation, and ionic bonding or lattice formation, etc., of tools that can consist of tool holders, tools, tool inserts, and other processing tools.

[0032] The following Figure 3 and Figure 4The basic configuration of the working zone with a gaseous medium is presented, which permeates all zones and surfaces to coordinate machining and cutting energy through charge exchange and ionic bonding. Another figure shows the basic temperature distribution on the tool and workpiece materials (heat released by energy conversion in the cutting zone), presenting primary (i), secondary (ii), and tertiary (iii) coordinator zones. Furthermore, depending on the material pair, coordination can further influence the tool and workpiece surfaces. The primary coordinator zone is at the workpiece and tool interface; therefore, in terms of elastoplastic deformation and its necessary heat generation (refer to plastic deformation), the primary coordinator zone does not have a negative impact on the internal shear and deformation zones. Moreover, it has a positive influence on the interactions of tool wear, such as plastic deformation, texture change, oxidation, and electrochemical reactions due to the characterized ion neutralization, recombination, or bonding, depending on the chosen workpiece and tool material pair. The charged gaseous medium surrounding the workpiece and tool in the cutting zone redistributes electrons in the metal in such a way that the charge of the medium is always attracted toward the metal surface, and interactions occur between the solid surface and the medium. In addition to the standard attractive interaction caused by vanishing waves, there is also the interaction caused by propagating Cherenkov waves. The repulsive interaction caused by waves. This fundamental electrodynamics must be considered whenever dealing with charge distribution.

[0033] When ionized atoms are projected onto a solid surface, an excited solid-atom system is formed. The ion neutralization process is the process by which the excited solid-atom system excites itself.

[0034] Metal surfaces are represented by Fermi levels (εF, the electrochemical potential of electrons in metals) and vacuum levels (εvac, the energy of electrons at rest in a vacuum, φ = work function).

[0035] Different neutralization (de-excitation) mechanisms can occur:

[0036] I) Resonance Neutralization: Electrons in the metal band tunnel from the surface to the excited state of the ion, and this excited state reacts with the surface state ( Figure 5 (a) together degrade energy.

[0037] II) Auger Neutralization: An electron in the metal band tunnels from the surface into a more tightly bound state of the ion. Energy is generated by the emission of a second (Auger) electron. Figure 5 (b) or photon ( Figure 5 (c) is conserved.

[0038] Auger electrons reside on the surface of a metal, and if the energy balance is positive, they can be excited above the vacuum level.

[0039] These processes are important because they play a role in secondary electron emission, gas discharge, and surface ionization mechanisms. The electron transitions involved in these processes are almost independent of the kinetic energy of the incident particle, but are governed by its excited potential energy.

[0040] Experimental studies on the relationship between current in the cutting zone and cutting edge wear revealed that when the workpiece is at the anode (positive electrode) and the cutting tool is at the cathode (negative electrode), the higher the cutting "thermocurrent," the greater its impact on wear intensity. The direction of the current depends on the chosen pair of workpiece and tool materials. In one case, an external current is applied directly to the tool at a certain voltage level; incorrect polarity causes increased tool wear compared to normal cutting settings. Therefore, it is crucial to understand the chosen materials and polarity in order to optimize the charged gas medium with the correct polarity.

[0041] The movement of ions in an electric field constitutes an electric current, the density of which depends on the number of ions in the air and their rate of movement away from or towards the source of the electric field. The relationship between current density and the electric field is called the conductivity of the air. This conductivity can vary with polarity. If an object is charged, an electric field is established around it. The field strength will vary from point to point but is always proportional to the charge. If an object is surrounded by air ions of two polarities, the current carried by ions with polarities opposite to their charges will flow towards the object. This neutralizing current is proportional to both the charge on the object and the relevant conductivity of the surrounding air. This neutralizing current is measured using a very sensitive Keithley measuring device when cutting a steel workpiece with a basic tungsten carbide tool (tool insert). Figure 6 In the presence of an ionized gas medium, the average current level was measured to be 0.75 mA, with a resonant range of 0.1 mA–1.6 mA. The sampling and recording time was 65 seconds. The parameters and polarity of the ionized gas medium can be measured and optimized using the electromotive force test settings described above.

[0042] The main parameters used for ionizing gaseous media are polarity, temperature, pressure of ionization flux, average ion density, and input pressure. Figure 7 and Figure 8 The diagram presents some basic values ​​for temperature and pressure, as well as ion density and pressure. A high density of ions is required to have any effect on the cutting zone. The medium temperature can be positive or negative, typically cold, as the medium temperature will support the current level in the cutting zone.

[0043] The electric field from the surrounding air containing the charged body creates a neutralizing current I–, which is also the rate of decay or neutralization of the total charge:

[0044]

[0045] in;

[0046]

[0047] And the time constant τ+ is:

[0048]

[0049] For a given ionic environment, the equations give the rate of neutralization by negatively charged air ions as a function of the geometry and dielectric position of the charges. Similar symmetric equations also apply to the neutralization of positive charges.

[0050] This invention was tested with several processing methods and materials. Typical methods were used to verify the test results. Some basic methods include tool wear analysis, such as flank and rake face wear, through mechanical, chemical, and visual methods. Surface roughness is also a typical method. Another novel method is acoustic emission (AE) measurement, which can display material plastic deformation, tool wear, chip formation, etc. This is an interesting approach to measuring the effects of coordinating cutting energy using an online method. This new method with an accurate force control system can be used for optimization of gas media for different materials. Thermal energy can also be measured using electromotive force methods, but it can also be derived from the force control results.

[0051] The figure below shows the results of different cutting tests using an Imara 520 round steel bar. Rake face wear was compared between the emulsion method and the method of this invention, where the method of this invention exhibited lower tool wear. The invention also improves machine surface roughness. RMS signals were measured using acoustic emission (AE) to compare friction values ​​between different cutting methods. Compared to other dry cutting methods, the method of this invention achieves lower friction signals and very stable results.

[0052] Table 2 below presents some cutting test settings for carbon steel at different cutting speeds. Coolant and eco-cooling (gas medium) were compared. The Ra value of the workpiece surface after cutting was at a good level.

[0053] carbon steel

[0054]

[0055] Table 2

[0056] Figure 9Some tool wear results from this cutting test are shown. The left side shows a tool insert with eco-cooling (gas medium), and the right side shows a tool insert with conventional coolant. A significant difference is evident; the use of conventional coolant results in much higher tool wear than the use of eco-cooling gas medium. There is considerable evidence of similar improvements where gas mediums can achieve the same or better cutting quality and improve tool life.

[0057] Therefore, the present invention relates to a method for processing workpiece material, the method comprising the steps of: selecting a pair of workpiece and tool materials; processing the workpiece material with the tool; and simultaneously providing a pressurized, cooled flow of an ionized gas medium to the working area, wherein the ionization level and polarity of the gas medium depend on the selected pair of workpiece and tool materials to coordinate the internal thermal energy and charge, enthalpy level and electrochemical reactions generated therein in the working area, workpiece and tool during processing.

[0058] In this method and apparatus, the ionization level and polarity of the gaseous medium can be controlled.

[0059] Furthermore, in this method and apparatus, the tool selection in a pair of choices may include the selection of tool shape and tool material.

[0060] Measurements such as electromotive force, internal charge (current, potential, electric field), AE, and other existing measurements can be used in this method and apparatus to optimize the performance according to the invention.

[0061] This invention has the ability to be implemented and utilized in several different machining methods, including milling, drilling, cutting, etc., including CNC and other machining centers. There are no limitations on applying this basic invention to a variety of machining processes.

[0062] It is clear from the foregoing that the present invention is not limited to the embodiments described herein, but can be implemented using many other different embodiments within the scope of the independent claims.

Claims

1. A method for processing workpiece material, the method comprising: - Select a pair of workpiece materials and tool materials. - The workpiece material is processed using the tool material; The feature is that machining is performed between the workpiece material and the tool material using electromotive force methods and thermionic and thermocurrent data to define the direction and polarity of the current, the direction and polarity of the current depending on the selected pair of workpiece materials and tool materials: - Generates a charged gas medium, the polarity of which depends on the selected pair of workpiece materials and tool materials; - Provide the external charged gas medium to the working area, the surface of the workpiece material and the tool material, and the interface; - During processing, the charged gas medium provides ion neutralization and / or recombination in the working area, the workpiece material, and the tool material; - Measure the parameters and polarity of the charged gas medium; - Controlling the ionization level and polarity of the charged gas medium, and The charged gas medium is air, nitrogen, or argon, depending on the selected pair of workpiece materials and tool materials.

2. The method according to claim 1, wherein, The charged gas medium is provided in the form of a flow.

3. The method according to claim 1 or 2, wherein, The charged gas medium has a temperature below or above 0°C, depending on the selected pair of workpiece materials and tool materials.

4. The method according to claim 1 or 2, wherein, The charged gas medium is generated by corona AC / DC or alpha ionization, collision, photoionization, or electrostatic spraying.

5. The method according to claim 1 or 2, wherein, The charged gas medium has positive, negative, or bipolar polarity, depending on the selected pair of workpiece materials and tool materials.

6. The method according to claim 1, wherein, The charged gas medium harmonizes internal thermal energy and charge / enthalpy levels through ion neutralization, recombination, and ion bonding in the working area, the workpiece material, and the tool material.

7. The method according to claim 1 or 6, wherein, The coordination via the charged gas medium is formed in different zones: primary, secondary, and tertiary coordinator zones, as well as the surfaces of the workpiece material and the tool material.

8. The method according to claim 1, wherein, Choose a pair of workpiece and tool materials from a group of conductive, non-conductive, or combined materials.

9. The method according to claim 1, wherein, The selected pair of workpiece materials and tool materials are partially or completely isolated or coated.

10. The method according to claim 1, wherein, Tool selection in a pair of material choices includes the selection of tool shape and tool material.

11. The method according to claim 1 or 10, wherein, The tool consists of a tool holder and tool inserts.

12. The method according to claim 1 or 2, wherein, The charged gas medium is optimized using a set of parameters including polarity, temperature, pressure of the charged gas medium, average ion density and input pressure, and temperature and input pressure, and based on the interaction of the parameters.

13. The method according to claim 1, wherein, At least one of electromotive force, internal charge, and AE is used in the method optimization.

14. The method according to claim 1, wherein, The charged gas medium minimizes cutting forces and tool wear by utilizing increased cutting speed and improved surface roughness.

15. The method according to claim 1, wherein, The charged gas medium supports the atomic repulsion force generated, thereby reducing the ionization energy of the workpiece material.

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