Process control method for axial linear dimension of inner groove of micro part

Abstract

This invention belongs to the field of machining technology, and particularly relates to a process control method for the axial linear dimension of the inner groove of a micro part. It includes: Step 1: Machining the inner hole and end face on the opposite side of the control edge of the inner groove to the theoretical size; Step 2: Machining the inner hole on the corresponding side of the control edge of the inner groove to a first size, where the first size is the theoretical value minus a first value b; Step 3: Determining the fillet radius R of the cutting tool; Step 4: Using a cutting tool with fillet radius R, machining the inner hole on the corresponding side of the control edge to the first size; Step 5: Using a cutting tool with fillet radius R, machining the inner groove to a first groove width, where the inner groove and the inner hole on the corresponding side of the control edge form a measuring surface; Step 6: Using a depth micrometer to measure the distance from the end face on the opposite side of the control edge to the measuring surface; Step 7: When the distance meets a threshold, using a cutting tool with fillet radius R, machining the inner hole on the corresponding side of the control edge of the inner groove to the theoretical size, at which point the inner groove width changes from the first groove width to the theoretical groove width.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, and in particular relates to a process control method for the axial linear dimension of the inner groove of a micro part. Background Technology

[0002] Features of directional valve parts: The total length of the parts is 13mm, the inner diameter is less than ф5mm, and the axial linear dimension tolerance of the inner groove is 0.02mm. Only by precisely controlling the axial linear dimension of the inner groove can the axial position of the sealing steel ball of the directional valve be guaranteed, thereby ensuring the low-pressure sealing performance and starting pressure of the product.

[0003] The reversing valve component has a small inner bore, and the axial linear dimension of the inner groove is a line-to-surface dimension. Currently, this cannot be measured during machining. The only method is to perform a first-piece sectioning, followed by dimensional measurement using a universal tool microscope. During the first-piece machining process, adjustments need to be made based on the measurement results. However, dimensional changes caused by tool wear during machining cannot be adjusted, resulting in dimensional deviations from acceptable tolerances. Summary of the Invention

[0004] Purpose of the invention: To provide a process control method for the axial linear dimension of the inner groove of a micro part, solving the problem that the axial linear dimension of the inner groove of a reversing valve and similar products cannot be detected by conventional means.

[0005] Technical solution:

[0006] A method for process control of the axial linear dimension of the inner groove of a micro part includes:

[0007] Step 1: Machin the inner hole and end face on the opposite side of the control edge of the inner groove to the theoretical dimensions;

[0008] Step 2: Machin the inner hole on the side corresponding to the control edge of the inner groove to the first dimension, which is the theoretical value minus the first value b;

[0009] Step 3: Determine the fillet radius R of the blade tip;

[0010] Step 4: Use a tool tip with a radius R to machine the inner hole on the corresponding side of the control edge to the first dimension;

[0011] Step 5: Using a tool tip with a rounded radius (R), machine the inner groove to the first groove width. The inner groove and the inner hole on the corresponding side of the control edge form a measuring surface.

[0012] Step 6: Use a depth micrometer to measure the distance from the end face on the opposite side of the control edge to the measuring surface;

[0013] Step 7: When the distance meets the threshold, use a tool tip with a rounded corner R to machine the inner hole on the side corresponding to the control edge of the inner groove to the theoretical size. At this time, the width of the inner groove changes from the first groove width to the theoretical groove width.

[0014] Furthermore, the first value b is greater than 0.5 mm.

[0015] Furthermore, the tool tip radius R is determined based on the axial dimensional accuracy.

[0016] Furthermore, when there are chamfers θ on both sides of the bottom of the inner tank and θ is less than 90°, the distance L from the end face of the opposite side of the control edge to the measuring surface satisfies: L measurement = L + a, where L is the theoretical axial distance of the inner tank control edge and a is the axial distance between the measuring surface and the control edge.

[0017] Furthermore, R < a < M, where M is the axial distance between the intersection of the extension of angle θ and the inner hole of the first size and the control edge, M = b / tanθ.

[0018] Furthermore, the first slot width = theoretical slot width + a.

[0019] Furthermore, the fillet radius R of the blade tip is less than or equal to 0.1 mm.

[0020] Furthermore, it also includes: Step 8: Perform a depth-of-cut pass on the control edge.

[0021] Beneficial effects:

[0022] This invention effectively solves the problem of detecting the axial linear dimensions of the inner groove during machining by using an intermediate transition control process. The first piece of the part no longer requires sectioning, and the machining process no longer requires sectioning to confirm dimensional machining quality and accuracy. At the same time, it avoids the problem of parts exceeding tolerances due to the inability to detect defects during machining.

[0023] This invention reduces the cutting, inspection, and waiting time in the part processing process, enables rapid inspection of the processing process, effectively ensures the quality of the parts, and achieves an axial linear dimension accuracy of 0.01mm for the inner groove edge of the part. Attached Figure Description

[0024] Figure 1 A schematic diagram illustrating the process control method for the axial linear dimension of the inner groove of a micro-part.

[0025] Figure 2 This is a dimensional control diagram illustrating the process control method for the axial linear dimension of the inner groove of a micro-part. Detailed Implementation

[0026] This invention employs an intermediate process to convert line-to-surface distances into surface-to-surface distances. A universal inspection method is used to check the inner groove dimensions, solving the problem of inspecting the axial linear dimensions of the inner groove during machining. After the first part is sectioned, it is inspected using a universal tool microscope. Due to the influence of sharp edges, burrs, and the radius of curvature of the sharp edges, the inspection error of the universal tool microscope is within 0.03mm. However, by using the intermediate process to inspect the surface-to-surface distances, a depth gauge with a dial indicator can be used, with an inspection accuracy of 0.002mm. The error of the reserved measurement surface allowance 'a' depends on the machine tool accuracy, and the axial accuracy of the machine tool is no greater than 0.003mm. Therefore, using the process method of this invention, the finishing and inspection accuracy can be controlled within 0.01mm, fully meeting the part requirements of ±0.02mm, and is superior to the original process. It also saves waiting time and improves processing efficiency.

[0027] This invention proposes a process method for intermediate transition control, reducing the size of the intermediate hole in the valve body of the directional valve (the size of the intermediate hole only relates to the size of the measuring surface and does not affect the final measurement accuracy), and converting the axial dimension of the inner groove from a line to a surface into a surface-to-surface distance, thus solving the problem of requiring sample sectioning for inspection. Figure 1 As shown. By setting intermediate process holes, the axial linear dimension of the inner groove edge is changed from a line to a surface to the dimension between two surfaces. The surface-to-surface inspection can be carried out using conventional metrology methods.

[0028] A process method for eliminating the tool tip radius (R) is proposed: by leaving a margin in the middle hole, the groove edge radius (R) extends downwards, which can then be removed during subsequent hole machining.

[0029] Forming the measuring plane directly from the groove edge will result in an inner radius (R) at the transition point (see...). Figure 2 This makes it impossible to eliminate in the end.

[0030] By controlling the tool tip radius (R), leaving a margin in the middle hole, and extending the groove edge radius (R) downwards, the radius (R) can be removed when passing through the subsequent machining hole.

[0031] Calculation scheme for measuring surface and groove width dimensions:

[0032] By measuring the actual value of the intermediate hole, where b is the hole allowance, the tool tip R≤0.1mm, and the measuring surface is a ring band b (axial offset dimension a of the measuring surface) of not less than 0.5mm, the hole allowance and θ angle are calculated, the measuring plane dimensions are determined, and a calculation formula for the measuring plane and groove width is proposed.

[0033] L_measurement = L + a (R < a < M, a is a constant) (1)

[0034] M = b / tanθ (2)

[0035] Groove width = Theoretical groove width + a(3)

[0036] Machin the intermediate hole and inner groove (without cutting to eliminate sharp edges and burrs) to the dimensions shown in the drawing, while ensuring the axial linear dimension of the inner groove edge.

[0037] By leaving a margin in the middle hole, the groove edge R extends downwards, increasing the width of the inner groove. This invention controls the groove width by setting an axial dimensional constant in the process plane.

[0038] A machining scheme for the process holes is proposed: The machining scheme for the process holes involves machining the intermediate hole and the inner groove. When machining the inner groove, the tool needs to be run in idle mode to eliminate sharp edge burrs.

[0039] Example:

[0040] A process control method for the axial linear dimension of the inner groove of a micro-part, wherein the theoretical values ​​of the inner holes on both sides of the inner groove of the micro-part are as follows:

[0041] Step 1: Machin the inner hole and end face on the opposite side of the control edge of the inner groove to the theoretical dimensions;

[0042] Step 2: Machin the inner hole on the side corresponding to the control edge of the inner groove to the first dimension, which is the theoretical value minus the first value b;

[0043] Step 3: Determine the fillet radius R of the blade tip;

[0044] Step 4: Use a tool tip with a radius R to machine the inner hole on the corresponding side of the control edge to the first dimension;

[0045] Step 5: Using a tool tip with a rounded radius (R), machine the inner groove to the first groove width. The inner groove and the inner hole on the corresponding side of the control edge form a measuring surface.

[0046] Step 6: Use a depth micrometer to measure the distance from the end face on the opposite side of the control edge to the measuring surface;

[0047] Step 7: When the distance meets the threshold, use a tool tip with a rounded corner R to machine the inner hole on the side corresponding to the control edge of the inner groove to the theoretical size. At this time, the width of the inner groove changes from the first groove width to the theoretical groove width.

[0048] In another possible embodiment, the first value b is greater than 0.5 mm.

[0049] In another possible embodiment, the tool tip radius R is determined based on the axial dimensional accuracy.

[0050] In another possible embodiment, when there are chamfers θ on both sides of the bottom of the inner tank and θ is less than 90°, the distance L from the end face of the opposite side of the control edge to the measuring surface is measured as follows: L measurement = L + a, where L is the theoretical axial distance of the inner tank control edge and a is the axial distance between the measuring surface and the control edge.

[0051] In another possible embodiment, R < a < M, where M is the axial distance between the intersection of the extension of angle θ and the inner hole of the first size and the control edge, and M = b / tanθ.

[0052] In another possible embodiment, the first slot width = theoretical slot width + a.

[0053] In another possible embodiment, the blade tip radius R is less than or equal to 0.1 mm.

[0054] In another possible embodiment, the method further includes: step 8: performing a depth-of-cut pass on the control edge to remove sharp edge burrs.

Claims

1. A method for process control of the axial linear dimension of the inner groove of a micro-part, characterized in that, include: Step 1: Machin the inner hole and end face on the opposite side of the control edge of the inner groove to the theoretical dimensions; Step 2: Machin the inner hole on the side corresponding to the control edge of the inner groove to the first dimension, which is the theoretical value minus the first value b; Step 3: Determine the fillet radius R of the blade tip; Step 4: Use a tool tip with a radius R to machine the inner hole on the corresponding side of the control edge to the first dimension; Step 5: Using a tool tip with a rounded radius (R), machine the inner groove to the first groove width. The inner groove and the inner hole on the corresponding side of the control edge form a measuring surface. Step 6: Use a depth micrometer to measure the distance from the end face on the opposite side of the control edge to the measuring surface; Step 7: If the distance meets the threshold, and there are no chamfers on both sides of the bottom of the inner groove, the inner hole on the side corresponding to the control edge of the inner groove is machined to the theoretical size using a tool tip with a rounded corner R. At this time, the width of the inner groove changes from the first groove width to the theoretical groove width. If there are chamfers θ on both sides of the bottom of the inner groove and θ is less than 90°, then the distance L from the end face of the opposite side of the control edge to the measuring surface satisfies: L measurement = L + a, where L is the theoretical axial distance of the inner groove control edge, a is the axial distance between the measuring surface and the control edge, and the first groove width = theoretical groove width + a.

2. The method according to claim 1, characterized in that, The first value b is greater than 0.5 mm.

3. The method according to claim 2, characterized in that, The tool tip radius R is determined based on the axial dimension accuracy.

4. The method according to claim 3, characterized in that, R < a < M, where M is the axial distance between the intersection of the extension of angle θ and the inner hole of the first dimension and the control edge, M = b / tanθ.

5. The method according to claim 3, characterized in that, The radius of the blade tip R is less than or equal to 0.1mm.

6. The method according to claim 3, characterized in that, Also includes: Step 8: Perform a depth-of-cut pass along the control edge.

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