Machining method and method for deriving groove machining conditions

Abstract

To suppress deformation due to residual stress.SOLUTION: In a machining method for manufacturing a product by machining a material: the material has a deformation mode and displacement amount corresponding to residual stress generated inside; and the deformation mode has a convex surface that protrudes outward. The method comprises the steps of: machining grooves to release residual stress in an excess thickness portion, which is a portion to become the convex surface and is obtained by subtracting a shape of the product from a shape of the material; and machining the material after the groove machining to manufacture the product.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a machining method and a method for deriving groove machining conditions.

Background Art

[0002] Conventionally, there is known a method for manufacturing a mold in which a groove is machined in a mold material to release the residual stress generated in the mold material, and then the mold material is engraved to manufacture a mold (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As shown in Patent Document 1, when machining a groove for releasing residual stress in a material in which residual stress is generated inside, it is formed on a concave surface that penetrates inside the mold material. However, even when groove machining is performed on the concave surface of the material, the residual stress cannot be appropriately released, and it has been difficult to suppress deformation generated in a product manufactured by machining the material.

[0005] Therefore, an object of the present disclosure is to provide a machining method and a method for deriving groove machining conditions capable of suppressing deformation due to residual stress.

Means for Solving the Problems

[0006] The machining method of this disclosure is a machining method for manufacturing a product by machining a material, wherein the material has a deformation mode and displacement amount corresponding to residual stress generated internally, the deformation mode has a convex surface that protrudes outward, and the method includes the steps of machining a groove to release the residual stress in the excess material portion which is the portion of the material that becomes the convex surface and is the portion obtained by subtracting the shape of the product from the shape of the material, and machining the material after the groove machining to manufacture the product.

[0007] The groove machining conditions derivation method of the present disclosure is a computer-operated method for deriving machining conditions for a groove to be machined in a material, for releasing residual stress generated inside the material, wherein the computer performs the steps of: acquiring the deformation mode and displacement of the actual material; creating a solid model that will be used as an analysis model for FEM analysis based on the shape of the material; and performing a simulated analysis that simulates the manufacturing process of the material, and introducing the residual stress into the solid model of the material so as to match the acquired deformation mode and displacement of the actual material. The process involves: setting the groove to be machined in the excess material portion, which is the portion obtained by subtracting the shape of the product from the shape of the material, with respect to the solid model into which the residual stress has been introduced, and which is a convex surface protruding outward from the material; setting the maximum depth of the groove within the range of the excess material portion; and performing an FEM analysis on the solid model into which the residual stress has been introduced, simulating the machining of the groove by the element extinction method, to obtain the deformation mode and displacement amount of the material, and deriving machining conditions for the groove such that the displacement amount is less than or equal to a predetermined amount.

[0008] The groove machining conditions derivation method of the present disclosure is a computer-based method for deriving groove machining conditions for a groove to be machined in a material, for releasing residual stress generated inside the material, wherein the computer performs the following steps: acquiring the deformation mode and displacement amount of the actual material; creating a cantilever model that serves as a calculation model for deflection calculation using material mechanics based on the shape of the material; setting the residual stress included in the cantilever model so as to match the acquired deformation mode and displacement amount of the actual material; setting the groove to be machined in the excess material portion, which is the portion obtained by subtracting the shape of the product from the shape of the material, and which is a convex surface protruding to the outside of the material, with respect to the cantilever model in which the residual stress has been set; setting the depth of the groove within the range of the excess material portion; and performing a deflection calculation using the cantilever model in which the groove has been machined based on the set groove depth, to derive groove machining conditions that are less than or equal to a predetermined displacement amount. [Effects of the Invention]

[0009] According to this disclosure, deformation due to residual stress can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an explanatory diagram of the machining method according to the first embodiment. [Figure 2] Figure 2 is a flowchart showing the method for deriving groove machining conditions according to the first embodiment. [Figure 3] Figure 3 is an explanatory diagram of the cantilever beam model used in the method for deriving groove machining conditions according to the second embodiment. [Figure 4] Figure 4 is an explanatory diagram of a grooved cantilever beam model used in the method for deriving groove processing conditions according to the second embodiment. [Figure 5] Figure 5 is a flowchart showing the method for deriving groove machining conditions according to the second embodiment. [Modes for carrying out the invention]

[0011] Embodiments relating to this disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit this disclosure. Furthermore, some components in the embodiments described below are substituted or substantially identical to those easily substituted by those skilled in the art. Moreover, the components described below can be combined as appropriate, and if there are multiple embodiments, each embodiment can be combined.

[0012] [First Embodiment] The machining method according to the first embodiment involves machining grooves into a material 5 that has internal residual stress, and then machining the grooved material 5 to manufacture a product 6. The method for deriving the groove machining conditions is a method for deriving the groove machining conditions for the material 5.

[0013] Figure 1 is an explanatory diagram of the machining method according to the first embodiment. Figure 2 is a flowchart of the method for deriving groove machining conditions according to the first embodiment. First, the machining method will be explained with reference to Figure 1.

[0014] (Machining method) As shown in Figure 1, the material 5 to be machined has a deformation mode and displacement amount corresponding to the residual stress generated internally. Material 5 is, for example, an extruded and solution-treated aluminum alloy. Note that material 5 is not particularly limited, and any material 5 that generates residual stress internally may be used for machining. As a deformation mode, material 5 has a bow-shaped deformation mode, for example, as shown in Figure 1, and the displacement amount is the amount of lift (warping) of both ends relative to the center. Because material 5 has a bow-shaped form, it has a convex surface that protrudes outward and a concave surface on the opposite side of the convex surface that is recessed inward.

[0015] In the machining method, step S1 of performing groove machining on the material 5 having an arcuate shape is executed. In step S1, groove machining is performed on the portion obtained by subtracting the shape of the product 6 from the shape of the material 5, that is, the surplus portion 7 of the material 5 that does not interfere with the product 6. When performing this groove machining, the deformation of the arcuate-shaped material 5 may be corrected with a clamp to make it flat and then machining may be performed. Also, in step S1, groove machining is executed on the convex surface portion of the material 5. The groove 8 formed by the groove machining is a groove for releasing the residual stress generated inside the material 5. The groove 8 is formed within the range of the surplus portion 7, and as the groove machining, at least one of slit machining for forming a bottomed slit and through-hole machining for forming a through-hole is executed. By performing this groove machining, the deformation of the material 5 is reduced, and it becomes possible to cut out the product 6 such as a part having a collected shape within the range of the surplus portion 7.

[0016] In the machining method, step S2 of fixing the groove-machined material 5 with the clamp jig 10 and machining the material 5 to manufacture a product is executed. When fixing the material 5 with the clamp jig 10, in order to minimize the deformation of the material 5, it is desirable to sandwich the shim 11 and generate as little deformation stress due to material correction as possible. In step S2, machining is executed in a state where the material 5 is corrected to a predetermined shape by the clamp jig 10. In step S2, since machining can be executed on the material 5 in which the residual stress has been released by the groove machining, the amount of displacement generated in the manufactured product 6 can be suppressed.

[0017] (Method for Deriving Groove Machining Conditions) In the above machining method, the groove machining conditions of the groove 8 machined in the material 5 are derived by the method for deriving groove machining conditions shown in FIG. Referring to FIG. 2, the method for deriving groove machining conditions will be described. In the method for deriving groove machining conditions, the following steps are executed by a computer.

[0018] In the method for deriving groove machining conditions, the computer executes step S11 of obtaining the deformation mode and displacement amount of the actual material (real material) 5 before machining. Subsequently, the computer executes step S12 of creating a solid model that becomes an analysis model for FEM analysis based on the shape of the material 5. The solid model generated in step S2 is an analysis model with material properties set, while it is an analysis model without the residual stress of the material 5 set.

[0019] After executing step S12, the computer executes step S13 of introducing residual stress into the solid model so as to match the deformation mode and displacement amount of the material 5 obtained in step S11. In step S13, the computer executes a simulation analysis of simulating the manufacturing process of manufacturing the material 5 to derive residual stress. In the manufacturing process of the material 5, a quenching process of quenching the material 5 and a stretch forming process of applying a tensile load to the material 5 to remove residual stress are executed. In step S13, the computer executes a thermo-elastic analysis for simulating the plastic deformation on the surface of the material 5 due to the quenching process and the cooling after the quenching process, to generate residual stress inside the solid model of the material 5. Thereafter, in step S13, the computer executes a plastic deformation analysis of simulating stretch forming on the solid model with residual stress applied in the thermo-elastic analysis, to remove the residual stress of the solid model of the material 5. Then, in step S13, the computer executes a simulation analysis of simulating the manufacturing process of the material 5 until the solid model after the removal of residual stress matches the deformation mode and displacement amount of the material 5 obtained in step S11. In step S13, the computer uses the solid model with residual stress introduced that matches the deformation mode and displacement amount of the material 5 obtained in step S11 as the initial solid model.

[0020] After step S13 is executed, the computer executes step S14, which sets grooves 8 in the excess material 7 that constitutes a convex surface of the material 5, for the solid model into which residual stress has been introduced. After step S14 is executed, the computer executes step S15, which sets the maximum depth of the grooves 8 within the range of the excess material 7. In step S15, if the excess material 7 can penetrate the grooves 8, the computer sets the maximum depth of the grooves 8 that will become through holes.

[0021] After step S15 is executed, the computer performs step S16, which simulates machining a groove 8 to the depth set in step S15 on a solid model into which residual stress has been introduced, and performs FEM analysis using the element elimination method. The machining conditions for the groove 8 to be machined can be set such that, if the difference between the intersecting short and long sides is large in the shape of the convex surface of the material 5, the groove 8 is set to be parallel to the short side, and if the difference between the intersecting short and long sides is small, the groove 8 may be set to be a grid-like groove with intersecting grooves. In step S16, the computer obtains the deformation mode and displacement amount of the material 5 after groove machining by performing FEM analysis using the element elimination method. Then, in step S16, the computer derives machining conditions for the groove 8 that result in a displacement amount less than or equal to a predetermined amount. For example, the computer performs FEM analysis based on multiple groove machining conditions and sets the condition that yields the greatest reduction in displacement as the groove machining condition.

[0022] Furthermore, when setting the groove machining conditions in step S16, it is desirable to set the spacing between the grooves 8 to a range of 1 / 10 to 1 / 30 of the long side of the convex surface of the material 5 as a guideline.

[0023] Furthermore, although step S13 was performed in the first embodiment, steps S14 to S16 may be performed without performing step S13, that is, without introducing residual stress into the solid model.

[0024] [Second Embodiment] Next, a second embodiment will be described with reference to Figures 3 to 5. Figure 3 is an explanatory diagram of a cantilever beam model used in the method for deriving groove machining conditions according to the second embodiment. Figure 4 is an explanatory diagram of a grooved cantilever beam model used in the method for deriving groove machining conditions according to the second embodiment. Figure 5 is a flowchart of the method for deriving groove machining conditions according to the second embodiment.

[0025] (Method for deriving groove machining conditions) The method for deriving groove machining conditions in the second embodiment differs from the method for deriving groove machining conditions in the first embodiment, and the groove machining conditions are derived by deflection calculation using a material mechanics calculation model.

[0026] In the method for deriving groove machining conditions, the computer performs step S21 to obtain the deformation mode and displacement of the actual material (real material) 5 before machining. Subsequently, the computer performs step S22 to create a cantilever beam model D, which will be a calculation model for deflection calculation using material mechanics, based on the shape of the material 5. In step S22, as shown in Figure 1, since the deformation mode of the material 5 is a bow shape, a cantilever beam model D is created with the central part of the material 5 as a fixed end and the ends of the material 5 as free ends.

[0027] Here, the displacement of the cantilever beam model D in a stress-free state when its own weight is added can be expressed as the sum of the six displacements of each beam element shown in equation (1) below.

[0028] δ=δ1+δ2+δ3+δ4+δ5+δ6 ···(1) δ: Deflection of beam element δ1: Deflection due to the self-weight of the beam element δ2: Deflection due to concentrated loads from other beam elements δ3: Deflection due to bending moment M from other beam elements δ4: Displacement due to the inclination θ of the beam due to deflection. δ5: Deflection due to the bending moment Mr of residual stress δ6: Displacement due to beam inclination φ, multiplied by the bending moment Mr of residual stress.

[0029] Furthermore, each beam element can be expressed by equations (2) to (7) below. Equations (2) to (7) will be explained based on the cantilever beam model D after groove processing shown in Figure 4.

[0030] δ1=ql 4 / 8EI ···(2) δ² = Pl 3 / 3EI ···(3) δ3 = Ml 2 / 2EI ···(4) δ₄=lsinθ ···(5) δ5=Mrl 2 / 2EI ···(6) δ6 = ltanφ ···(7) q: Uniformly distributed load due to its own weight l: Beam length ql: own weight M: Bending moment P: Concentrated load due to the weight of other elements I: Second moment of area of ​​a beam element E: Young's modulus Mr: Bending moment due to residual stress

[0031] The bending moment Mr of residual stress can be determined by processing a portion of the actual material and using the formula "Mr = E(I0 / R0 - I1 / R1)" to find the change in its bending curvature R.

[0032] After step S22 is executed, the computer executes step S23 to set up the cantilever beam model D so that it matches the deformation mode and displacement of material 5 obtained in step S21. In other words, in step S23, the bending moment Mr of the residual stress is derived and introduced into the cantilever beam model D. The computer then uses the cantilever beam model D with the introduced residual stress that matches the deformation mode and displacement of material 5 obtained in step S21 as the initial cantilever beam model D.

[0033] After step S23 is performed, the computer performs step S24 to set grooves 8 in the excess material 7, which is a convex portion of the material 5, for the cantilever beam model D into which residual stress has been introduced. After step S24 is performed, the computer performs step S25 to set the maximum depth of the grooves 8 within the range of the excess material 7. In step S25, if the excess material 7 can penetrate the grooves 8, the computer sets the maximum depth of the grooves 8 that will become through holes.

[0034] After step S25 is executed, the computer executes step S26 to set up a cantilever beam model D with grooves 8 machined into it, compared to the cantilever beam model D into which residual stress has been introduced. In step S26, as shown in Figure 4, multiple grooves 8 to be machined are set in the cantilever beam model D, and a deflection calculation based on equations (2) to (7) is performed based on the set multiple grooves 8. Then, in step S26, the computer performs a deflection calculation using the cantilever beam model D with grooves 8 machined into it, based on the depth of the grooves 8 set in step S25. In step S26, the computer obtains the deformation mode and displacement of the material 5 after groove machining by performing the deflection calculation. Then, in step S26, the computer derives the machining conditions for the grooves 8 that result in a displacement less than or equal to a predetermined amount. For example, the computer performs a deflection calculation based on multiple groove machining conditions and sets the condition that yields the greatest reduction in displacement as the groove machining condition.

[0035] In the second embodiment, when creating the cantilever beam model D in step S22, residual stress was introduced into the cantilever beam model D by adding equations (6) and (7), but equations (6) and (7) may be omitted.

[0036] As described above, the machining method and the method for deriving groove machining conditions described in the first and second embodiments can be understood, for example, as follows.

[0037] The machining method according to the first embodiment is a machining method for manufacturing a product 6 by machining a material 5, wherein the material 5 has a deformation mode and displacement amount corresponding to the residual stress generated inside, the deformation mode has a convex surface that protrudes outward, and the method includes the steps of: performing groove machining to release the residual stress in the excess material portion 7 which is the convex portion of the material 5 and is the portion obtained by subtracting the shape of the product 6 from the shape of the material 5; and machining the material 5 after groove machining to manufacture the product 6.

[0038] With this configuration, by machining grooves on the convex surface of material 5, the residual stress of material 5 can be appropriately released. Then, by machining material 5 from which the residual stress has been appropriately released, a product 6 with suppressed deformation can be manufactured.

[0039] In a second embodiment, the machining method according to the first embodiment is a grooving process within the range of the excess material portion 7, and includes at least one of a slitting process to form a slit and a through-hole to form a through-hole.

[0040] With this configuration, groove machining that appropriately releases residual stress can be performed within the excess material portion 7 of the material 5.

[0041] A third embodiment of a method for deriving groove machining conditions is a computer-operated method for deriving machining conditions for a groove 8 machined in a material 5, the groove 8 being machined to release residual stress generated inside the material 5, the method comprising: a step S11 in which the computer acquires the deformation mode and displacement amount of the actual material; a step S12 in which the computer creates a solid model that will be used as an analysis model for FEM analysis based on the shape of the material 5; and a step S12 in which the computer performs a simulated analysis that simulates the manufacturing process of the material 5 and introduces the residual stress into the solid model of the material 5 so as to match the acquired deformation mode and displacement amount of the actual material. Step S13 is performed, and Step S14 is performed to set the groove 8 to be machined in the excess material portion 7, which is the portion obtained by subtracting the shape of the product 6 from the shape of the material 5, and which is a convex surface that protrudes to the outside of the material 5, for the solid model into which the residual stress has been introduced, Step S15 is performed to set the maximum depth of the groove 8 within the range of the excess material portion 7, and Step S16 is performed to perform an FEM analysis on the solid model into which the residual stress has been introduced, simulating the machining of the groove 8 by elemental extinction method, to obtain the deformation mode and displacement amount of the material 5, and to derive machining conditions for the groove 8 that are less than or equal to a predetermined displacement amount.

[0042] This configuration allows for the appropriate deriving of machining conditions for grooves 8 machined into the convex surface of material 5. By performing groove machining based on these deriving conditions, the residual stress in material 5 can be appropriately released. Then, by machining material 5 from which residual stress has been appropriately released, a product 6 with suppressed deformation can be manufactured.

[0043] In a fourth aspect, in the method for deriving groove machining conditions according to the third aspect, the simulated analysis that simulates the manufacturing process includes a thermo-elastoplastic analysis that simulates a quenching treatment of the material and an elastoplastic analysis that simulates forming of the material.

[0044] This configuration allows for the appropriate simulation of the manufacturing process of material 5, and enables the setting of residual stresses based on the manufacturing process in the solid model of material 5.

[0045] A fifth method for deriving groove machining conditions is a computer-based method for deriving machining conditions for a groove 8 machined in a material 5, which is used to release residual stress generated inside the material 5, the method comprising: a step S21 in which the computer acquires the deformation mode and displacement of the actual material; a step S22 in which the computer creates a cantilever beam model D which is a calculation model for deflection calculation using material mechanics based on the shape of the material; and a step S22 in which the cantilever beam model D including the residual stress is adjusted to match the acquired deformation mode and displacement of the actual material. Step S23 is to set up the groove 8, which is to be machined in the excess material portion 7, which is the portion obtained by subtracting the shape of the product 6 from the shape of the material 5, with respect to the cantilever beam model D including the residual stress, and which is a convex surface that protrudes to the outside of the material 5, Step S24 is to set up the groove 8 to be machined in the excess material portion 7, Step S25 is to set up the depth of the groove 8 within the range of the excess material portion 7, and Step S26 is to perform a deflection calculation using the cantilever beam model D with the groove 8 machined based on the set depth of the groove 8, and derive machining conditions for the groove 8 that will be less than or equal to a predetermined displacement.

[0046] This configuration allows for the appropriate deriving of machining conditions for grooves 8 machined into the convex surface of material 5. By performing groove machining based on these deriving conditions, the residual stress in material 5 can be appropriately released. Then, by machining material 5 from which residual stress has been appropriately released, a product 6 with suppressed deformation can be manufactured. [Explanation of Symbols]

[0047] 5 Materials 6 Products 7 Extra meat part 8 grooves

Claims

1. A method for deriving groove machining conditions, which is performed by a computer, for deriving machining conditions for a groove to be machined in a material, in order to release residual stress generated inside the material, The machining of the groove is at least one of slitting to form a bottomed slit and through-hole machining to form a through hole. The aforementioned computer, Steps include obtaining the deformation mode and displacement amount of the actual material, The steps include creating a solid model that will serve as the analysis model for FEM analysis based on the shape of the material, The steps include: performing a simulated analysis that simulates the manufacturing process of the material, and introducing the residual stress into the solid model of the material so that it matches the deformation mode and displacement amount of the actual material obtained; The steps include setting the grooves to be machined in the excess material portion, which is the portion obtained by subtracting the shape of the product from the shape of the material, with respect to the solid model into which the residual stress has been introduced, and which is a convex surface that protrudes outward from the material; The steps include setting the maximum depth of the groove within the range of the excess material, A method for deriving groove machining conditions, comprising the steps of: performing a FEM analysis on the solid model into which the residual stress has been introduced, simulating the machining of the groove by the element extinction method, to obtain the deformation mode and displacement of the material, and deriving groove machining conditions such that the displacement of the material after groove machining, obtained from the execution of the FEM analysis, is less than or equal to a predetermined displacement.

2. The method for deriving groove machining conditions according to claim 1, wherein the simulated analysis for simulating the manufacturing process includes a thermo-elastoplastic analysis for simulating a heat treatment of the material and an elastoplastic analysis for simulating forming of the material.

3. A method for deriving groove machining conditions, which is performed by a computer, for deriving machining conditions for a groove to be machined in a material, in order to release residual stress generated inside the material, The machining of the groove is at least one of slitting to form a bottomed slit and through-hole machining to form a through hole. The aforementioned computer, Steps include obtaining the deformation mode and displacement amount of the actual material, The steps include creating a cantilever beam model that serves as a calculation model for deflection calculation using material mechanics based on the shape of the material, The steps include setting up the cantilever beam model, including the residual stress, so as to match the deformation mode and displacement amount of the acquired actual material, The steps include setting the groove to be machined in the excess material portion, which is the portion obtained by subtracting the shape of the product from the shape of the material, with respect to the cantilever beam model including the residual stress, and which is a convex surface that protrudes outward from the material, Within the range of the excess material, the steps include setting the depth of the groove, A method for deriving groove machining conditions, comprising the steps of: performing a deflection calculation using the cantilever beam model in which the groove has been machined based on the set groove depth to obtain the deformation mode and displacement amount of the material, and deriving groove machining conditions such that the displacement amount of the material after groove machining obtained in the deflection calculation is less than or equal to a predetermined displacement amount.

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