Precise grinding method for double end faces of high-hardness large-face thin plate
By employing alternating grinding on both ends and staged optimization of grinding parameters, the problem of deformation during grinding of high-hardness, large-area, and ultra-thin plate parts was solved, achieving efficient and stable shape and position accuracy control and meeting multiple accuracy requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-22
- Publication Date
- 2026-04-07
AI Technical Summary
During the double-end grinding process of high-hardness, large-area, ultra-thin, and high-precision plate parts, the workpiece is prone to complex deformation due to factors such as transient thermal shock, elastic/plastic bending caused by grinding force, and residual stress release. Single-sided grinding can easily disturb the accuracy of the other side, making it difficult to achieve stable control of form and position accuracy.
The double-end-face alternating grinding method is adopted, which alternately grinds the two end faces of the workpiece. Each grinding is carried out until the nitrided layer is completely removed on at least 40% of the area of one end face. Combined with staged optimization of grinding parameters, large depth of cut and small depth of cut are used alternately to control the form and position integration degree within the preset threshold and achieve dynamic stress balance.
It effectively suppresses workpiece deformation, ensures that multiple precision requirements such as flatness, parallelism, equal thickness tolerance, and surface roughness are met simultaneously, improves process stability and product consistency, and avoids efficiency loss and workpiece damage caused by ineffective over-grinding.
Smart Images
Figure CN121798441A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of grinding technology, specifically to a method for precision grinding of double-end faces of high-hardness, large-area thin plates. Background Technology
[0002] The swashplate is a key functional component in a swashplate piston hydraulic pump. It is installed between the swashplate seat and the slipper, fixed to the swashplate seat with screws, and remains relatively stationary during operation. The slipper slides back and forth at high speed on its surface, maintaining close contact with the slipper, thereby driving the piston movement. This structure has a decisive impact on the system's dynamic response speed, operational stability, and overall reliability.
[0003] As attached Figure 1 As shown, the swashplate 10 has the following typical structural and precision characteristics:
[0004] 1. High hardness requirement: The material is 38CrMoAl alloy steel, and the surface hardness is not less than HV1000 after nitriding treatment to ensure wear resistance;
[0005] 2. Large-area thin plate structure: As a common support platform for the synchronous operation of 9 sets of sliding shoes, its area size a×b reaches 305mm×300mm, while the thickness is only 5mm, which is a typical large-area, ultra-thin plate part.
[0006] 3. Irregular structure: To meet assembly and connection requirements, the workpiece has multiple connection hole systems and asymmetrical four-corner contours, resulting in uneven rigidity distribution;
[0007] 4. Ultra-high form and position accuracy requirements: To ensure smooth movement of the slipper and minimize frictional power consumption, its double end faces must meet the following requirements: flatness ≤ 0.005mm, parallelism ≤ 0.01mm, equal thickness tolerance ≤ 0.01mm, and surface roughness Ra ≤ 0.2μm.
[0008] Due to the combined effects of the above characteristics, this type of workpiece exhibits extremely high process sensitivity during double-end precision grinding. The transient thermal shock during grinding, the elastic / plastic bending induced by grinding force, the dynamic release of residual stress, the warping tendency in the four corner areas, and the springback after unloading from the magnetic chuck all interact and can easily lead to complex deformations. Particularly noteworthy is the strong deformation coupling effect between the two end faces; grinding one side directly disturbs the geometry of the other, causing repeated fluctuations in accuracy. Even if the workpiece temporarily meets the drawing requirements after machining, its accuracy may still degrade during storage or use as residual stress continues to be released.
[0009] Therefore, the double-end grinding of high-hardness, large-area, ultra-thin, and high-precision plate parts, represented by swashplates, has long been a recognized technological challenge in the field of precision manufacturing. Summary of the Invention
[0010] The purpose of this invention is to provide a precision grinding method for double-end faces of high-hardness, large-area thin plates, which can effectively suppress deformation and achieve coordinated control of form and position accuracy.
[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0012] This application discloses a method for precision grinding of double-end faces of a high-hardness, large-area thin plate, comprising: providing an initial plate material, wherein the initial plate material is a nitrided 38CrMoAl thin plate material with a thickness not exceeding 5mm; the form and position integration degree of the initial plate material is less than or equal to a first preset threshold, wherein the form and position integration degree is: under a unified measurement reference, the local thickness difference at corresponding points in space between the two end faces in the thickness direction of the workpiece, i.e., the maximum deviation of the thickness values between all corresponding points; performing semi-finish grinding on the initial plate material, setting the grinding parameters for semi-finish grinding, and alternately grinding the two end faces in the thickness direction of the initial plate material until the nitriding color on both end faces is completely removed; performing finish grinding on the initial plate material, setting the grinding parameters for finish grinding, and alternately grinding the two end faces in the thickness direction of the initial plate material until both faces can be completely ground in one pass with a single cutting depth, and the final form and position integration degree is less than or equal to a second preset threshold.
[0013] Furthermore, during the alternating grinding process of semi-fine grinding and fine grinding, each time any end face is ground, the grinding is stopped only when at least 40% of the area of that end face is completely removed, and the workpiece is flipped to grind the other end face, and this cycle is repeated.
[0014] Furthermore, the first preset threshold is 0.05 mm, and the second preset threshold is 0.006 mm.
[0015] Furthermore, the grinding parameters of the semi-finish grinding include: a total grinding amount of 0.010mm to 0.014mm per round and a depth of cut of 0.001mm to 0.003mm per pass.
[0016] Furthermore, the grinding parameters for the fine grinding include: a total grinding amount of 0.004mm to 0.006mm per round and a depth of cut of 0.001mm per pass.
[0017] The present invention has the following unexpected beneficial effects:
[0018] 1. This invention employs a dual-end-face alternating grinding strategy, ensuring that the two end faces of the workpiece remain in a dynamic stress balance state during the grinding process. This effectively suppresses bending deformation induced by concentrated cutting force and thermal load on one side. Even when one end face is close to its final size, it is still forced to continue participating in micro-grinding, thereby achieving real-time tracking and coordinated reduction of machining deformation. This fundamentally avoids the process instability phenomenon of "grinding one side and bending the other side" in traditional single-sided grinding.
[0019] 2. This invention creatively proposes "form and position integration degree" as a unified process control index, defined as: the maximum absolute value of the difference in local thickness values at corresponding points in space on two end faces of a workpiece under a unified measurement benchmark. This parameter has a clear physical meaning, quantifiability, and measurability. Engineering practice verification shows that when the final form and position integration degree is controlled within a second preset threshold, multiple original design accuracy requirements such as flatness, parallelism, thickness tolerance, and surface roughness can be simultaneously met, significantly simplifying the multi-objective coupled control problem and improving process stability and product consistency.
[0020] 3. This invention achieves a balance between efficiency and precision by optimizing grinding parameters in stages. In the semi-finish grinding stage, a relatively large single-pass depth of cut and total grinding volume per pass are used to efficiently remove the nitrided layer and initially correct macroscopic deformation. In the finish grinding stage, the depth of cut and grinding volume per pass are switched to a smaller amount, combined with a dynamic grinding rule that flips the blade when 40% of the single-sided grinding area is reached, precisely controlling residual deformation. While ensuring the final surface roughness and dimensional accuracy, this effectively avoids the loss of processing efficiency or the risk of workpiece damage caused by ineffective over-grinding. Attached Figure Description
[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.
[0022] Figure 1 This is a schematic diagram of the swashplate.
[0023] Figure 2 This is a schematic diagram of the markings on the initial sheet metal provided in an embodiment of this application.
[0024] Figure 3 This is a schematic diagram of the grinding process provided in an embodiment of this application.
[0025] Figure 4 This is a schematic diagram of the shape and position comprehensiveness measuring device described in the embodiments of this application.
[0026] Reference numerals: 1-Workpiece, 2-Measuring platform, 3-Indicator holder, 4-Dial indicator, 10-Swashplate, 20-Initial sheet material. Detailed Implementation
[0027] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.
[0028] In one embodiment, this application discloses a method for precision grinding of double-end faces of a high-hardness, large-area thin plate, comprising the following steps:
[0029] S1, provide an initial sheet material, which is a nitrided 38CrMoAl thin sheet with a thickness of no more than 5mm; the form and position integration degree of the initial sheet material is less than or equal to a first preset threshold, and the form and position integration degree is: under a unified measurement reference, the local thickness range of the two end faces of the workpiece in the thickness direction at corresponding points in space, that is, the maximum deviation of the thickness values between all corresponding points.
[0030] See Figure 2 As shown, the convex end face of the initial sheet 20 is defined as end face A, and the concave end face of the initial sheet 20 is defined as end face B.
[0031] The measurement of the geometrical integration degree described in this invention is achieved through the following steps:
[0032] S11, Prepare the measuring device, see below. Figure 4 As shown, a high-precision measuring platform 2, such as a marble reference platform, is used, with its surface serving as a unified measurement reference surface. A dial indicator frame 3 is installed on the measuring platform 2, and a dial indicator 4 is fixed on the frame 3. The probe of the dial indicator 4 is perpendicular to the surface of the measuring platform 2 and is used to collect the height data of the end face of the workpiece 1.
[0033] S12, Workpiece Placement and Positioning: Place workpiece 1 (i.e., the initial sheet metal 20 or the processed workpiece) stably and freely on the measuring platform 2, avoiding additional deformation caused by clamping force. Workpiece 1 should be kept horizontal to ensure that both end faces in its thickness direction can be effectively measured.
[0034] S13, A-side measurement: Place the probe of dial indicator 4 in contact with one end face of workpiece 1 (denoted as A-side), and measure its height relative to the measuring platform 2 point by point on a predetermined grid (e.g., one point every 10mm × 10mm). Record the values of all points.
[0035] S14, Flip the workpiece and measure surface B. Carefully flip workpiece 1 so that its other end face (denoted as surface B) faces upwards, and place it stably again on the same measuring platform 2, ensuring that its spatial coordinate system is aligned with that of surface A during measurement. This can be achieved through edge positioning or auxiliary positioning blocks. Using the same dial indicator 4, measure the corresponding point at the same position as surface A. Measure the height value of side B. .
[0036] S15, for each set of corresponding points Calculate its local thickness deviation: .
[0037] S16, take all corresponding points The maximum value of this value is the form and position comprehensiveness of the workpiece. .
[0038] This application creatively proposes "form and position integration degree" as a unified process control index, defined as: the maximum absolute value of the difference in local thickness values at corresponding points in space on two end faces of a workpiece under a unified measurement datum. This parameter has a clear physical meaning, quantifiability, and measurability. Engineering practice verification shows that when the final form and position integration degree is controlled within a second preset threshold, multiple original design accuracy requirements such as flatness, parallelism, thickness tolerance, and surface roughness can be simultaneously met, significantly simplifying the multi-objective coupled control problem and improving process stability and product consistency.
[0039] S2, see S2. Figure 3 As shown, the initial sheet material is semi-finished. The semi-finishing grinding parameters are set, and the two end faces in the thickness direction of the initial sheet material are alternately ground until the nitriding color on the two end faces is completely removed.
[0040] S3. Perform fine grinding on the initial sheet material, set the grinding parameters for fine grinding, and alternately grind the two end faces of the initial sheet material in the thickness direction until both faces can be completely ground in one go with a single cut, and the final shape and position integration degree is less than or equal to the second preset threshold.
[0041] This application employs a dual-end-face alternating grinding strategy, ensuring that the two end faces of the workpiece remain in a dynamic stress balance state during the grinding process. This effectively suppresses bending deformation induced by concentrated cutting force and thermal load on one side. Even when one end face is close to its final size, it is still forced to continue participating in micro-grinding, thereby achieving real-time tracking and coordinated reduction of machining deformation. This fundamentally avoids the process instability phenomenon of "grinding one side and bending the other side" in traditional single-sided grinding.
[0042] In a preferred embodiment of this application, during the alternating semi-fine and fine grinding process, each time any end face is ground, grinding is stopped only when at least 40% of the area of that end face is completely removed, and the workpiece is flipped to grind the other end face. This process is repeated. This rule uses the area of nitride layer removal as an intuitive and discernible criterion for process termination. It ensures that each grinding action covers a sufficient area to stimulate the overall elastic response, while retaining the unground area as rigid support, achieving dynamic compensation of deformation on both sides. This operating principle is simple, executable, and does not rely on operator experience, significantly improving the stability and yield of mass production.
[0043] In a preferred embodiment of this application, the first preset threshold is 0.05 mm and the second preset threshold is 0.006 mm.
[0044] In this preferred embodiment, by explicitly limiting the initial form and position integral degree to ≤0.05 mm, a clear, quantifiable, and detectable quality output standard is set for the preceding processes (such as nitriding heat treatment, stress-relieving annealing, rough grinding, etc.). Only when the preceding processes ensure that the deformation of the billet is controlled within this threshold can the subsequent double-end-face alternating grinding strategy effectively play its role. Extensive process testing has verified that when the initial form and position integral degree of the sheet metal is ≤0.05 mm, the double-end-face alternating grinding method described in this invention can achieve a final form and position integral degree of ≤0.006 mm with 100% success rate.
[0045] During the grinding process, when the overall form and position accuracy was detected to be ≤0.006mm, the five key form and position accuracy indicators were verified by a coordinate measuring machine, and the results all met the design requirements. For example, the five form and position accuracy indicators include: flatness of surface A ≤0.005mm, flatness of surface B ≤0.005mm, parallelism of the two surfaces ≤0.010mm, equal thickness tolerance ≤0.010mm, and surface roughness ≤0.2μm.
[0046] In a preferred embodiment of this application, the grinding parameters for the semi-finish grinding include: a total grinding amount per round of 0.010 mm to 0.014 mm, and a depth of cut of 0.001 mm to 0.003 mm per pass. The grinding parameters for the finish grinding include: a total grinding amount per round of 0.004 mm to 0.006 mm, and a depth of cut of 0.001 mm per pass.
[0047] During the semi-finish grinding stage, the nitrided layer has high hardness and uneven thickness, and the workpiece exhibits macroscopic bending or warping. By using a relatively large grinding depth per pass (0.010mm~0.014mm) and a moderate depth of cut (0.001mm~0.003mm), the surface nitriding color and major geometric deviations can be removed quickly and uniformly while ensuring the effective cutting capability of the grinding wheel, avoiding grinding burns or low efficiency caused by insufficient feed.
[0048] During the finishing grinding stage, the workpiece is close to its target size, and residual deformation is mainly due to microscopic elastic recovery. Switching to a low depth of cut (0.001 mm) and a small pass size (0.004 mm to 0.006 mm) at this stage significantly reduces the grinding force and heat input per unit area, effectively suppressing elastic deflection or thermal warping of thin plates caused by transient loads, ensuring stable and consistent precision. If semi-finishing grinding parameters are still used during the finishing grinding stage, excessive pursuit of surface finish can lead to multiple passes of idling grinding without substantial precision improvement, wasting time, accelerating CBN wheel wear, and potentially inducing springback deformation due to cumulative thermal effects. This solution, by precisely differentiating stage objectives and eliminating ineffective grinding, shortens the single-piece processing time while ensuring quality and extending wheel life.
[0049] This application achieves a balance between efficiency and precision by optimizing grinding parameters in stages. In the semi-finish grinding stage, a relatively large single-pass depth of cut and total grinding volume per pass are used to efficiently remove the nitrided layer and initially correct macroscopic deformation. In the finish grinding stage, the process switches to a smaller depth of cut and smaller grinding volume per pass, combined with a dynamic grinding rule that flips the surface when 40% of the grinding area on one side is reached, precisely controlling residual deformation. While ensuring the final surface roughness and dimensional accuracy, this effectively avoids the risk of processing efficiency loss or workpiece damage caused by ineffective over-grinding.
[0050] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.
Claims
1. A method for precision grinding of double-end faces of a high-hardness, large-area thin plate, characterized in that, include: An initial sheet material is provided, which is a nitrided 38CrMoAl thin sheet with a thickness of no more than 5 mm. The form and position integration degree of the initial sheet material is less than or equal to a first preset threshold. The form and position integration degree is defined as the local thickness difference at corresponding points in space between two end faces in the thickness direction of the workpiece under a unified measurement datum, i.e., the maximum deviation of thickness values between all corresponding points. The initial sheet material is semi-finished by setting the semi-finished grinding parameters and alternately grinding the two end faces in the thickness direction of the initial sheet material until the nitriding color on both end faces is completely removed. The initial sheet material is then finely ground by setting the fine grinding parameters and alternately grinding the two end faces in the thickness direction of the initial sheet material until both sides can be completely ground in one pass with a single cut amount, and the final form and position integration degree is less than or equal to a second preset threshold.
2. The method for precision grinding of double-end faces of high-hardness, large-area thin plate parts according to claim 1, characterized in that: During the alternating grinding process of semi-fine grinding and fine grinding, each time any end face is ground, the grinding is stopped only when at least 40% of the area of that end face is completely removed, and the workpiece is flipped to grind the other end face. This process is repeated.
3. The method for precision grinding of double-end faces of high-hardness, large-area thin plate parts according to claim 1, characterized in that: The first preset threshold is 0.05mm, and the second preset threshold is 0.006mm.
4. The method for precision grinding of double-end faces of high-hardness, large-area thin plate parts according to claim 1, characterized in that, The grinding parameters for the semi-finish grinding include: a total grinding amount of 0.010mm to 0.014mm per round and a depth of cut of 0.001mm to 0.003mm per pass.
5. The method for precision grinding of double-end faces of high-hardness, large-area thin plate parts according to claim 1, characterized in that, The grinding parameters for the fine grinding include: a total grinding amount of 0.004mm to 0.006mm per round and a depth of cut of 0.001mm per pass.