CN110340739B - Metal smooth grinding method based on thermal control - Google Patents

Metal smooth grinding method based on thermal control Download PDF

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CN110340739B
CN110340739B CN201910603293.5A CN201910603293A CN110340739B CN 110340739 B CN110340739 B CN 110340739B CN 201910603293 A CN201910603293 A CN 201910603293A CN 110340739 B CN110340739 B CN 110340739B
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diamond
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grinding wheel
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workpiece
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CN110340739A (en
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谢晋
何铨鹏
卢阔
罗宜毫
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South China University of Technology SCUT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B47/00—Drives or gearings; Equipment therefor
    • B24B47/20—Drives or gearings; Equipment therefor relating to feed movement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B53/00—Devices or means for dressing or conditioning abrasive surfaces
    • B24B53/06—Devices or means for dressing or conditioning abrasive surfaces of profiled abrasive wheels

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Abstract

The invention discloses a metal smooth grinding method based on thermal control, which comprises the following steps: utilizing iron electrode to implement mechanical thermochemical smoothing of diamond on the ring surface of grinding wheel so as to make the diamond smooth areas c 1/4 greater than the cross-sectional area of the diamond; the diamond grinding wheel moves in a radial feeding mode, and the motion parameters of the machine tool are controlled to ensure the actual cutting depth of the diamondh r Greater than the critical conversion depth of abrasive grain plow-cuttingh cr Grinding and cutting the surface layer material of the metal workpiece by using diamond; when the radial feeding is finished once, the diamond grinding wheel moves along the direction vertical to the cutting direction of the grinding wheel and finishes the grinding processing in sequence in a circulating way. According to the invention, the diamond grinding wheel does not need to be sharpened repeatedly, good surface integrity of the workpiece can be obtained only by controlling the motion parameters of the machine tool and utilizing the flattened diamond on the ring surface of the grinding wheel to carry out rolling cutting, and the flattened diamond is not easy to fall off and graphitize, so that the requirements of high-efficiency and high-surface-quality grinding of the metal workpiece difficult to cut can be met.

Description

Metal smooth grinding method based on thermal control
Technical Field
The invention relates to the technical field of diamond grinding wheel grinding, in particular to a metal smooth grinding method based on thermal control.
Background
Difficult-to-cut metal materials such as titanium alloy and die steel are widely applied to the fields of aerospace, precision equipment manufacturing, automobiles, medical treatment and the like, and the processing technology of the difficult-to-cut metal materials often represents or restricts the development level of the national mechanical industry and other related industries. In the precision grinding of difficult-to-cut metal materials, abrasive grain edge-exposure characteristic parameters are key factors influencing the processing quality of the surface of a workpiece, the abrasion of a grinding wheel and the removal of materials, so that a CBN grinding wheel which has the granularity of less than 50 mu m and has hardness second to that of diamond but chemical inertness to iron group metals and alloys thereof is generally adopted to meet the requirements of surface quality and processing precision, but the grinding wheel is easy to abrade, high-efficiency processing is difficult to realize, and cutting fluid is required to be adopted in the process to prevent the thermal damage generated on the surface of the workpiece.
To solve this problem, "a mirror grinding method of a rough diamond grinding wheel", [ patent No.: CN201810088140.7, application date: 2018.01.30, discloses a method for mirror grinding metal material by using a flattened rough diamond grinding wheel, which is based on the following principle: and carrying out dry grinding on the surface of the metal workpiece by using the flattened rough diamond grinding wheel in an axial, small-cutting-depth and slow-feeding mode so as to obtain good workpiece surface processing quality. However, this technique has the following disadvantages:
1. the problem of diamond graphitization abrasion caused by instantaneous high temperature and grinding force when a metal workpiece which is difficult to cut is ground is not considered, and the abrasive particle abrasion can directly influence the surface integrity of the workpiece;
2. the continuous contact time between the workpiece surface layer material and the smoothing diamond is long in the axial feeding mode, and the smoothing diamond and the workpiece surface are easy to form sliding friction and plowing by small cutting depth and slow feeding, which can cause thermal damage to the workpiece surface layer, especially in dry grinding.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a metal smooth grinding method based on thermal control, which does not need to adopt cutting fluid, only needs to control the motion parameters of a machine tool to ensure that the actual cutting depth of a diamond is greater than the plowing-cutting critical conversion depth of abrasive particles, utilizes the flattened diamond on the annular surface of a grinding wheel to carry out rolling cutting in a radial feeding mode to obtain good surface integrity of a workpiece, and can ensure that the diamond is not easy to fall off and graphitize in the grinding process by controlling the flattened area of the diamond.
The technical scheme for solving the technical problems is as follows:
a metal smooth grinding method based on thermal control comprises the following steps:
in the grinding wheel dressing stage, the iron electrode is utilized to carry out mechanical thermochemical dressing on the diamond on the grinding wheel ring surface so as to enable the diamond to be dressed to have an area sc1/4 greater than the cross-sectional area of the diamond;
in the smooth grinding stage, the diamond grinding wheel moves in a radial feeding mode, and the motion parameters of the machine tool are controlled to ensure the actual cutting depth h of the diamondrGreater than the critical conversion depth h of abrasive grain plow-cuttingcrGrinding and cutting the surface layer material of the metal workpiece by using diamond;
and when the primary radial feeding is finished, the diamond grinding wheel moves for 10-100 mu m along the direction vertical to the cutting direction of the grinding wheel and then is machined again, and the machining is circulated in sequence to finally form a smooth and flat macroscopic mirror surface on the surface of the metal workpiece gradually.
The scheme flattens the diamond by the area scThe reason why the temperature rise rate of the diamond surface layer and the temperature rise value of the workpiece surface layer are both controlled to be greater than the diamond sectional area 1/4 is that the temperature rise rate of the diamond surface layer and the temperature rise value of the workpiece surface layer are related to the diamond flattening area, the diamond surface layer in grinding can be effectively prevented from graphitizing and wearing by utilizing the good heat conduction performance of the flattened diamond, and most heat in the grinding area is led out from the diamond flattening surface, so that the heat damage of the workpiece surface layer can be prevented.
Aiming at the problem of heat damage of the surface layer of the workpiece, the grinding wheel is also considered to move in a radial feeding mode in the grinding process, and the actual cutting depth of the diamond is larger than the abrasive particle plow-cutting critical conversion depth by controlling the motion parameters of a machine tool, because the continuous contact time of the material of the surface layer of the workpiece and the smoothing diamond can be reduced by radial feeding, and the smooth scraping and plowing between the smoothing diamond and the surface of the workpiece can be effectively avoided by increasing the actual cutting depth.
Further, the machine motion parameter is determined by equation (1):
Figure BDA0002119992900000031
in the formula, N, vfAnd apThe parameters of the machine tool motion are respectively the grinding wheel rotating speed, the worktable feeding speed and the cutting depth, and D is the grinding wheel diameter.
Further, the mechanical thermochemical flattening mode of the diamond is as follows: connecting an iron electrode, a diamond grinding wheel and a direct current power supply to form a discharge circuit, wherein the iron electrode is connected with a negative electrode, and the diamond grinding wheel is connected with a positive electrode; the diamond grinding wheel cuts the iron electrode in a radial feeding mode, the motion parameters of a machine tool are controlled in the cutting process, so that the electric spark discharge voltage is stabilized in a range of 2-5V lower than the open-circuit voltage, and the diamond surface layer is graphitized under the action of mechanical heat and discharge heat and is gradually removed under the action of mechanical force.
Further, the rolling cutting mode of the surface layer material of the metal workpiece is as follows: the diamond is cut into the metal workpiece in a high-speed rotating state, and the cutting surface and the flattening surface of the diamond sequentially carry out micro-removal and rolling on a surface layer material of the workpiece. According to the scheme, the cutting surface and the flattening surface are used for sequentially removing and rolling the material of the surface layer of the workpiece.
In the scheme, in addition to the thermal damage of the surface layer of the workpiece, the grinding force between the diamond and the surface of the workpiece is also a main factor influencing the surface quality of the workpiece, the grinding force is related to the diamond smoothing area, and compared with a dressing diamond, the dressing diamond is used for cutting the surface layer material of the workpiece and rolling simultaneously, so that the plastic deformation of the material caused by the diamond acting force can be reduced.
Further, the granularity of the diamond grinding wheel is #40 to # 270.
The reason for using #40 to #270 is that the diamond chip removal capacity is highly related to the edge cutting height of the abrasive particles, the chips which cannot be removed in the dry grinding process can damage the surface integrity of the workpiece (such as forming scratches and attachments), and the smooth grinding of the fine diamond grinding wheel with the size of #270 is difficult to realize.
Further, the hardness of the metal workpiece is 20-100 HRC.
Further, when processing a metal workpiece having a hardness of less than 60HRC, dry grinding is used, otherwise wet grinding is used. Since the existing research shows that the grinding force is in positive correlation with the hardness of the workpiece, the dry grinding mainly avoids the thermal damage of the surface layer of the workpiece through the heat conduction of diamond, and when the grinding force is increased, partial heat of the grinding area needs to be taken away by using the cutting fluid.
Compared with the prior art, the invention has the following beneficial effects:
1. the flattened rough diamond grinding wheel is not abraded basically in the grinding process, and the diamond is not easy to graphitize, so that the grinding wheel is not required to be sharpened repeatedly, and the processing efficiency is improved while the processing quality is ensured;
2. the diamond grinding machine improves the cutting performance of diamond, does not need to adopt a CBN grinding wheel aiming at the grinding of metal workpieces, can obtain good surface integrity of the workpieces only by controlling the motion parameters of the machine tool and utilizing the flattened diamond on the ring surface of the grinding wheel to grind and cut, and has flexible and convenient processing mode.
3. The flattened diamond is used for rolling and cutting in a radial feeding mode, so that the surface layer of the workpiece can be prevented from being thermally damaged, and cutting fluid is not needed in the process of a metal workpiece with the hardness of less than 60HRC, so that the method is a green and environment-friendly processing and manufacturing technology.
Drawings
Fig. 1a is a topographical map of a sharpened diamond.
FIG. 1b is a topographical map of a flattened diamond.
Fig. 2 is a schematic view of a smooth grinding mode.
FIG. 3 is a graph showing the effect of different grinding methods on the surface roughness of a workpiece.
Fig. 4a is a schematic view of the action of a sharpening diamond on the surface of a workpiece.
FIG. 4b is a schematic view of the action of the smoothing diamond on the surface of the workpiece.
Figure 5a is a graph of the effect of sharpening and flattening diamonds on the grinding force coefficient.
FIG. 5b is a graph of the effect of sharpening and flattening diamonds on the temperature rise value of a workpiece.
Figure 5c is a graph of the effect of flattened area on diamond temperature rise rate.
FIG. 6a is a surface topography profile of a workpiece dry ground with a dressing CBN wheel.
FIG. 6b is a topographical map of the workpiece surface wet ground with a dressing CBN wheel.
FIG. 6c is a graph of the topography of the surface of a workpiece dry-ground with a dressing diamond wheel.
FIG. 6d is a surface topography profile of a workpiece dry ground with a smoothing diamond wheel.
Fig. 7 is a macroscopic mirror surface of the die steel after smooth grinding.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
A metal smooth grinding method based on thermal control comprises the following steps:
s1, grinding wheel dressing stage, using iron electrode to do mechanical thermal chemical flat to the diamond on the grinding wheel ring surface to make the diamond flat area Sc1/4 greater than the cross-sectional area of the diamond;
s2, in the smooth grinding stage, the diamond grinding wheel moves in a radial feeding mode, and the motion parameters of the machine tool are controlled to ensure the actual cutting depth h of the diamondrGreater than the critical conversion depth h of abrasive grain plow-cuttingcrGrinding and cutting the surface layer material of the metal workpiece by using diamond;
and S3, when the primary radial feeding is finished, the diamond grinding wheel moves for 10-100 mu m along the direction vertical to the cutting direction of the grinding wheel and then is machined again, and the steps are sequentially circulated to finally enable the surface of the metal workpiece to gradually form a smooth and flat macro mirror surface.
Referring to fig. 1 to 7, taking a #46 grinding wheel (diamond or CBN, diameter D150 mm, concentration 75%) as an example for grinding die steel with hardness of 55HRC, the working principle of the metal smoothing grinding method based on thermal control of the present invention is described in detail, and the technical effects of the present invention are further verified.
The topographical features of the dressed diamonds are shown in FIG. 1a, and the abrasive grains A, B and C observed on the segments of the grinding wheel were investigated, and the abrasive grains dressed with oilstone had sharp cutting edge tips with an average tip area and tip width of about 3500 μm2And 106 μm. Performing mechanical thermochemical smoothing on the diamond on the ring surface of the grinding wheel, connecting an iron electrode (No. 45 steel, -), a diamond grinding wheel (+) and a direct current power supply (DCS80) to form a discharge loop, cutting the iron electrode by the diamond grinding wheel in a radial feeding mode, and setting initial smoothing parameters to beThe open-circuit voltage is 25V, the current limiting value is 0.1A, the rotating speed of a grinding wheel is 2400rpm, the feeding speed of a workbench is 80mm/min, the cutting depth is 1 mu m, the moving distance of a Z axis is 1mm, the motion parameters of a machine tool are adjusted on line in the process to enable the electric spark discharge voltage to be stabilized within the range of 19-23V, and the diamond surface layer is graphitized under the action of mechanical heat and discharge heat and is gradually removed under the action of mechanical force. Topographic characterization of the flattened diamonds As shown in FIG. 1B, the sharp cutting tips of abrasive grains A, B and C were removed to form a flat surface with an average flattened area and flattened width (typically 1/2 for abrasive grain size) of about 27500 μm2And 205 μm.
As shown in fig. 2, the diamond grinding wheel grinds the metal workpiece in a radial feeding manner (moving along the X axis of the grinding wheel cutting direction), and when the radial feeding is completed for one time, the diamond grinding wheel moves along the direction (Z axis) perpendicular to the grinding wheel cutting direction by a distance Δ Z and then is machined again, and the process is circulated in sequence to gradually form a smooth and flat macro mirror surface on the surface of the workpiece. Research shows that the workpiece surface roughness is reduced along with the reduction of the Z-axis moving distance, and the workpiece surface processing quality can be improved by controlling the Z-axis moving distance within 1/2 of the diamond flattening width, namely, the Delta Z is 10-100 mu m.
In order to verify the grinding effect of the radial feeding mode, the influence of four processing modes of radial dry grinding, radial water grinding, axial dry grinding and axial water grinding on the surface roughness of the workpiece is contrastively analyzed. The axial feeding mode is that the diamond grinding wheel moves along a Z axis vertical to the cutting direction of the grinding wheel, and when the axial feeding is completed for one time, the diamond grinding wheel moves for a distance delta X along the cutting direction (X axis) of the grinding wheel and then is machined again. A grinding experiment is carried out on the die steel by using the flattened #46 diamond grinding wheel, and the grinding parameters are set to be 2400rpm of the rotation speed of the grinding wheel, 200mm/min of the feeding speed of a workbench, 2 mu m of cutting depth and 15 mu m of Z-axis moving distance. The effect of different grinding methods on the surface roughness of the workpiece is shown in fig. 3, and compared with axial feeding, radial feeding reduces the surface roughness of the workpiece by about 40%, and the surface roughness of the workpiece obtained by radial dry grinding is minimum and can reach 146 nm. Therefore, the purpose of adopting the radial feeding mode to carry out smooth grinding in the technology is to improve the surface processing quality of the workpiece.
The theoretical verification on how to improve the cutting performance and avoid graphitized abrasion of the flattened diamond so as to improve the surface processing quality and the processing efficiency of the workpiece can be verified.
The sharpening and flattening diamonds act on the surface of a workpiece as shown in fig. 4, the diamonds act on the workpiece during grinding to generate tangential grinding force and normal grinding force, the tangential grinding force raises the temperature of the workpiece and the surface layer of the diamonds, and the normal grinding force plastically deforms the processing surface of the workpiece. Wherein the tangential grinding force and the cutting force sigma of the diamond unit cross section area0In relation to the normal grinding force and the mean contact pressure p of the diamond against the surface of the workpiecedRelated, mean temperature rise of workpiece Δ TgwsAnd rate of diamond temperature rise Δ TgdAnd the area of the top end of the abrasive grain (i.e., the flattened area s)c) And (4) correlating. As can be seen from the comparative analysis of the topography of the sharpening and flattening diamonds, the sharpening diamonds slightly remove the material of the surface of the workpiece through the cutting surface, but cannot perform grinding due to the small area of the top end of the abrasive grain (see fig. 4 a); the smoothing diamond can sequentially remove and roll the workpiece surface layer material through the cutting surface and the smoothing surface, thereby improving the workpiece surface processing quality (as shown in fig. 4 b).
In addition, the grinding wheel rotating speed N is 2400rpm and the worktable feed speed v is calculated through the established grinding force model and the workpiece temperature field distribution model respectivelyf500mm/min, depth of cut apGrinding force coefficient (cutting force of diamond per unit cross-sectional area sigma) corresponding to sharpening and flattening diamond under 8 mu m0And average contact pressure pd) And the temperature rise value of the workpiece (the total temperature rise value Delta T of the workpiece caused by all the working diamonds on the ring surface of the grinding wheelgwtAnd the average temperature rise value Delta T of the workpiece caused by a single diamond participating in workinggws) The results are shown in FIGS. 5a and 5 b. Cutting force per unit cross-sectional area σ of the flattened diamond as compared with the sharpened diamond0The variation is not significant, but the average contact pressure pdThe reduction is about 10 times, and the elastoplasticity mechanics research shows that the elastoplasticity deformation generated on the surface of the object is in positive correlation with the surface acting force of the object, so that the flattened diamond can obtain good surface integrity; good flattening of diamondThe heat conductivity of the diamond grinding wheel leads most heat in a grinding area to be derived from a diamond plane, and the average temperature rise value delta T of a workpiecegwsThe reduction is about 2.5 times, even if the total temperature rise value of the workpiece is increased by only 10 percent under the condition of increasing the mechanical friction action, which indicates that the flattening diamond can prevent the surface layer of the workpiece from being thermally damaged.
Studies have shown that the duller the abrasive tip (i.e., the larger the flattened area), the greater the critical depth of abrasive plow-cut transition. When the diamond forms a sliding and plowing brush with the surface of the workpiece, the chip is difficult to form (namely, the surface energy which is basically not deformed by the chip in the process is consumed), and the heat generated by continuous mechanical friction action can be accumulated on the surface layer of the workpiece to cause thermal damage. Therefore, the actual cutting depth h of the diamond in the smooth grinding is controlled by controlling the motion parameters of the machine toolrGreater than the critical conversion depth h of abrasive grain plow-cuttingcrAccording to the relative motion relationship between the diamond and the workpiece, the following can be obtained:
Figure BDA0002119992900000081
research shows that atoms such as iron, chromium, titanium and the like have strong attraction to cubic carbon in diamond, and instantaneous high temperature and grinding force generated when difficult-to-cut metal workpieces such as titanium alloy, die steel and the like are ground can cause graphitized abrasion of the diamond. Calculating the rotating speed N of the grinding wheel to be 2400rpm and the feeding speed v of the workbench by the established diamond temperature field distribution modelf500mm/min, depth of cut apTemperature rise rate Δ T of diamond at 8 μmgd. The influence of the flattened area on the diamond temperature rise rate is shown in FIG. 5c, the diamond temperature rise rate Δ TgdArea s to be flattenedcIs increased and decreased when the diamond is flattened by the area scFrom 3500 μm2Increased to 27500 μm2Time, temperature rise rate Δ T of diamond surface (y ═ 0)gdThe temperature was abruptly decreased from 540 ℃ to 76 ℃. Compared with a dressing diamond, the dressing diamond is not easy to graphitize and wear in grinding.
In summary, the technology of the present invention flattens the area s of the diamondcControlled to be larger than the diamond sectionThe purpose of area 1/4 is to improve diamond cutting performance while avoiding graphitized wear of the diamond surface layer and thermal damage to the workpiece surface layer during grinding.
The key point of using the flat diamond to realize the smooth grinding of the metal workpiece difficult to cut lies in how to solve the influence of the heat of the grinding area on the temperature rise of the surface layer of the workpiece/diamond. In the mirror surface grinding method of the rough diamond grinding wheel, the flat diamond is only used for grinding the metal workpiece, and the flat area of the diamond, the grinding mode and the set motion parameters of the machine tool are not controlled to avoid thermal damage of the surface layer of the workpiece and graphitization of the surface of the diamond, so that the surface quality of the machined workpiece is difficult to reach the mirror surface level.
It should be emphasized that the technology of the present invention is not a simple superposition of the prior art, and the essential difference is that the cutting performance of the smoothing diamond is better than that of the smoothing diamond, but the mechanical friction between the smoothing diamond and the metal workpiece in the grinding increases the heat of the grinding area, and the diamond smoothing area and the machine tool motion parameters are controlled to avoid the sharp increase of the temperature of the workpiece/diamond surface layer, so as to obtain good grinding cutting effect of the workpiece, which is not the basic knowledge in the field. Due to the difference of the action mode and mechanism of the diamond, even if the person skilled in the art combines the basic common knowledge in the field and limited experiments, the diamond flattening area and the control range of the motion parameters of the machine tool defined by the invention can not be obtained.
The following comparative analysis of the grinding effects of the dressing/smoothing diamond wheel and the dressing CBN wheel by examples shows the feasibility of the metal workpiece smooth grinding method of the present invention.
Examples
The method comprises the steps of utilizing a diamond grinding wheel which is subjected to mechanical thermochemical leveling, a diamond grinding wheel which is subjected to oilstone sharpening and a CBN grinding wheel, and adopting a radial feeding mode to carry out grinding experiments on die steel, wherein the grinding depth h of abrasive grain plow-cutting critical conversion of leveling diamond is consideredcrAbout 0.25 μm, the machine motion parameters were determined according to the formula (1) to be the grinding wheel rotation speed 2400rpm, the table feed speed 500mm/min, the cutting depth 8 μm, and the Z-axis movement distance was set to 15 μm.The topography of the surface of the workpiece by dry grinding and wet grinding with the dressing CBN grinding wheel is shown in fig. 6a and 6b, and the thermal damage of the surface of the workpiece caused by dry grinding with the dressing CBN grinding wheel is more severe than that of wet grinding, resulting in an increase in the surface roughness of the workpiece obtained by about 1 time than that of wet grinding. The surface topography of the work piece dry ground by the dressing diamond wheel and the dressing diamond wheel is shown in fig. 6c and 6d, the surface of the work piece obtained by grinding the dressing diamond wheel is smooth and has no thermal damage, and the surface roughness of the work piece is reduced by 75 percent and 65 percent compared with the surface roughness of the work piece obtained by dry grinding and wet grinding of the dressing diamond wheel and the dressing CBN wheel, and can reach 78 nm. Based on the grinding experiments described above, a polished diamond wheel was used to further dry grind a macroscopic mirror surface on the die steel surface (see fig. 7). This shows that the grinding effect of the flat diamond is better than that of the sharp diamond and CBN, and the flat diamond can be used for smooth grinding of metal workpieces.
It should be emphasized that, in the dry grinding of the smoothing diamond, the heat damage of the surface layer of the workpiece is mainly avoided by the heat conduction of the diamond, although the heat conductivity of the diamond can reach 2000W/(m · K), the heat of the grinding area increases with the increase of the grinding force (related to the hardness of the workpiece), when the grinding force reaches a certain critical value, the heat damage of the surface layer of the workpiece cannot be completely avoided only by the heat conduction of the diamond, and it is necessary to take away part of the heat of the grinding area by the cutting fluid. Experimental studies have shown that dry grinding can be used when machining die steels with hardness less than 60HRC, so the technique of the present invention limits the application range of smoothing diamond dry grinding to metal workpieces with hardness less than 60 HRC.
In conclusion, the smoothing diamond is used for grinding in a mode of radial feeding and controlling the motion parameters of the machine tool, so that not only can good surface integrity of the workpiece be obtained, but also the diamond is not easy to fall off and graphitized and worn, and the requirements of high-efficiency and high-surface-quality processing of metal workpieces difficult to cut can be met.
The present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.

Claims (5)

1. A metal smooth grinding method based on thermal control is characterized by comprising the following steps:
in the grinding wheel dressing stage, the iron electrode is utilized to carry out mechanical thermochemical dressing on the diamond on the grinding wheel ring surface so as to enable the diamond to be dressed to have an area sc1/4 greater than the cross-sectional area of the diamond; the mechanical thermal chemical flattening mode of the diamond is as follows: connecting an iron electrode, a diamond grinding wheel and a direct current power supply to form a discharge circuit, wherein the iron electrode is connected with a negative electrode, and the diamond grinding wheel is connected with a positive electrode; the diamond grinding wheel cuts the iron electrode in a radial feeding mode, the motion parameters of a machine tool are controlled in the cutting process to enable the electric spark discharge voltage to be stabilized in a range of 2-5V lower than the open-circuit voltage, and the diamond surface layer is graphitized under the action of mechanical heat and discharge heat and is gradually removed under the action of mechanical force;
in the smooth grinding stage, the diamond grinding wheel moves in a radial feeding mode, and the motion parameters of the machine tool are controlled to ensure the actual cutting depth h of the diamondrGreater than the critical conversion depth h of abrasive grain plow-cuttingcrGrinding and cutting the surface layer material of the metal workpiece by using diamond; the rolling cutting mode of the surface layer material of the metal workpiece is as follows: the diamond is cut into the metal workpiece in a high-speed rotating state, and the cutting surface and the flattening surface of the diamond sequentially carry out micro-removal and rolling on a material of the surface of the workpiece;
and when the primary radial feeding is finished, the diamond grinding wheel moves for 10-100 mu m along the direction vertical to the cutting direction of the grinding wheel and then is machined again, and the machining is circulated in sequence to finally form a smooth and flat macroscopic mirror surface on the surface of the metal workpiece gradually.
2. The thermal control based metal smoothing grinding method of claim 1, wherein:
the machine tool motion parameter is determined by equation (1):
Figure FDA0003068243550000011
in the formula, N, vfAnd apThe parameters of the machine tool motion are respectively the grinding wheel rotating speed, the worktable feeding speed and the cutting depth, and D is the grinding wheel diameter.
3. The metal smoothing grinding method based on thermal control according to claim 1 or 2, characterized in that: the granularity of the diamond grinding wheel is #40 to # 270.
4. The metal smoothing grinding method based on thermal control according to claim 1 or 2, characterized in that: the hardness of the metal workpiece is 20-100 HRC.
5. The thermal control based metal smoothing grinding method of claim 4, wherein: when processing a metal workpiece with the hardness of less than 60HRC, dry grinding is adopted, otherwise, wet grinding is adopted.
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2877962Y (en) * 2006-04-18 2007-03-14 李广庆 Electronic numerical control diamond grinding wheel finishing machine
CN102019585A (en) * 2010-10-09 2011-04-20 华南理工大学 Method for precisely finishing V-shaped sharp corner of diamond grinding wheel based on numerical control mutual wear molding
CN102490121A (en) * 2011-11-24 2012-06-13 华南理工大学 Method for finishing V-shaped sharp angle of metal-base diamond grinding wheel by electrical discharge grinding in gas
CN103395002A (en) * 2013-07-24 2013-11-20 华南理工大学 In-gas discharge dressing and truing method for large-particle diamond grinding wheel
CN103770006A (en) * 2014-01-22 2014-05-07 西安工业大学 Method for finishing diamond grinding wheel by utilizing electric spark, as well as disc-shaped electrode and device adopted
CN107598723A (en) * 2017-09-13 2018-01-19 华南理工大学 The micro- sophisticated abrasive particle electrothermal chemical retapering device of emery wheel and its On-Line Control Method
CN108161743A (en) * 2018-01-30 2018-06-15 深圳大学 The discharge finishing screeding device and method of brait grinding wheel
CN108177030A (en) * 2018-01-30 2018-06-19 华南理工大学 A kind of mirror grinding method of brait grinding wheel
CN108747822A (en) * 2018-06-04 2018-11-06 哈尔滨工业大学 A kind of preparation method of novel diamond wheel and the efficient ultraprecise processing method of micro structure array

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2877962Y (en) * 2006-04-18 2007-03-14 李广庆 Electronic numerical control diamond grinding wheel finishing machine
CN102019585A (en) * 2010-10-09 2011-04-20 华南理工大学 Method for precisely finishing V-shaped sharp corner of diamond grinding wheel based on numerical control mutual wear molding
CN102490121A (en) * 2011-11-24 2012-06-13 华南理工大学 Method for finishing V-shaped sharp angle of metal-base diamond grinding wheel by electrical discharge grinding in gas
CN103395002A (en) * 2013-07-24 2013-11-20 华南理工大学 In-gas discharge dressing and truing method for large-particle diamond grinding wheel
CN103770006A (en) * 2014-01-22 2014-05-07 西安工业大学 Method for finishing diamond grinding wheel by utilizing electric spark, as well as disc-shaped electrode and device adopted
CN107598723A (en) * 2017-09-13 2018-01-19 华南理工大学 The micro- sophisticated abrasive particle electrothermal chemical retapering device of emery wheel and its On-Line Control Method
CN108161743A (en) * 2018-01-30 2018-06-15 深圳大学 The discharge finishing screeding device and method of brait grinding wheel
CN108177030A (en) * 2018-01-30 2018-06-19 华南理工大学 A kind of mirror grinding method of brait grinding wheel
CN108747822A (en) * 2018-06-04 2018-11-06 哈尔滨工业大学 A kind of preparation method of novel diamond wheel and the efficient ultraprecise processing method of micro structure array

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
《砂轮表面形貌定量评价及修整效果研究》;刘伟等;《中国机械工程》;20181030;第29卷(第19期);第2277-2283页 *

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