A jig for measuring the dimensions of irregularly shaped arc-shaped products

Abstract

This application discloses an auxiliary fixture for measuring the dimensions of irregularly shaped arc-shaped products, including a fixture body and a clamping assembly. The fixture body is made of Cr12MoV alloy steel, with a precision-machined positioning plane and an integrally formed positioning edge on the top. An auxiliary guide rod is vertically fixed on the left side of the spring mounting hole. The clamping assembly includes a stainless steel compression spring and a pressure block with an adaptable arc-shaped pressing surface. This fixture solves the problems of unstable positioning, large measurement errors, and easy product damage in existing solutions. It can control the measurement error within 0.005mm, achieve rapid product positioning, avoid surface scratches, and is durable and adaptable to various arc-shaped products, effectively improving the measurement accuracy and efficiency of irregularly shaped arc-shaped products in the MIM industry.

Description

Technical Field

[0001] This utility model relates to the technical field of measurement auxiliary equipment in the metal injection molding (MIM) industry, specifically to an auxiliary fixture for measuring the dimensions of irregularly shaped arc-shaped products. It can be used with a two-dimensional measuring instrument to achieve high-precision positioning and detection, solving the measurement problem caused by the small reference surface and high proportion of arc surface in irregularly shaped arc-shaped products. Background Technology

[0002] In the MIM (Metal Injection Molding) production process, irregularly shaped arc-shaped products (such as typical dimensions of 22.59×6.97×2.98mm) are one of the core product categories. These products have two key characteristics: first, the reference surface is very small (usually only accounting for 10%-15% of the product's surface area); second, the outer surface is mainly arc-shaped (accounting for over 70%). Currently, the industry generally adopts a "free placement + manual alignment" method for measuring the dimensions of such products, that is, the product is directly placed on the worktable of the 2D measuring instrument, and the product's posture is manually adjusted before measurement. This method has the following unavoidable technical defects: 1. Lack of positioning reference and large measurement error: The existing solution does not have a dedicated positioning plane and reference edge, and it is necessary to directly take lines on the tiny reference surface of the product. The line taking error of the two-dimensional measuring instrument can reach 0.03mm. However, the tolerance zone of such products is usually only 0.06mm, and the measurement error accounts for as much as 50%. This can easily lead to "qualified products being misjudged as unqualified" (over-rejection) or "unqualified products being missed", resulting in a fluctuation of ±10% in the product transfer pass rate, which seriously affects the mass production and delivery efficiency.

[0003] 2. Unstable product positioning and difficulty in controlling horizontal displacement: The arc-shaped structure makes it impossible for the product to fit stably against the measuring table, and it is easy to tilt when placed manually; in addition, there is no auxiliary positioning structure, and the product is prone to horizontal displacement due to airflow and table vibration, which further amplifies the measurement error. A single measurement requires repeated adjustments 3-5 times to complete, taking as long as 40-60 seconds.

[0004] 3. Unreasonable clamping structure, easy product damage: Although some solutions attempt to use simple clamping blocks, the clamping blocks are not designed to fit the arc surface, which can easily scratch the outer arc surface of the product (damage rate of about 5%). In addition, the clamping force is not precisely controlled (too much will cause product deformation, too little will not be able to fix it), and it is impossible to balance "fixation stability" and "surface protection".

[0005] 4. Poor durability of fixtures and easy loss of accuracy: Most existing auxiliary tools are made of ordinary steel without hardening treatment. After high-frequency use (more than 1,000 measurements per day), the reference surface is prone to wear and deformation, and the accuracy decreases by 0.008-0.01mm per month. Frequent calibration is required (2-3 times per month), which increases maintenance costs.

[0006] In summary, existing technologies lack dedicated auxiliary fixtures that can integrate "high-precision reference, stable positioning, adaptable clamping, and durable protection," thus failing to meet the MIM industry's demand for high-precision and high-efficiency measurement of irregularly shaped arc products. Utility Model Content

[0007] The purpose of this utility model is to provide an auxiliary fixture for measuring the dimensions of products with irregular arc structures, so as to provide a high-precision positioning reference, avoid product misjudgment, achieve rapid positioning, ensure the matching of clamping force, improve the durability of the fixture, reduce the attenuation of accuracy, and reduce maintenance costs.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is: an auxiliary fixture for measuring the dimensions of irregularly shaped arc structure products, including a fixture body and a clamping assembly; The top of the fixture body is provided with a positioning plane, which is precision machined by a grinding machine to ensure the flatness of the measurement reference. The fixture body is integrally formed with a positioning edge along the edge of the positioning plane. The positioning edge is set perpendicular to the positioning plane and is used as a reference line for two-dimensional measurement. The clamping assembly includes a pressure block and a spring. The spring is elastically connected between the fixture body and the pressure block. The side of the pressure block facing the positioning plane is used to fit against the irregular arc structure product. The elastic force of the spring presses the product against the positioning plane, so that the reference surface of the product fits tightly against the positioning plane, thereby achieving the positioning and fixing of the product.

[0009] In a preferred embodiment, the flatness tolerance of the positioning plane is ≤0.002mm, the perpendicularity tolerance of the positioning edge is ≤0.001mm, and the straightness tolerance of the positioning edge is ≤0.001mm.

[0010] In a preferred embodiment, the fixture body has a spring mounting hole extending through its thickness direction. The spring is fitted into the spring mounting hole, with one end of the spring abutting the bottom end face of the spring mounting hole and the other end fixedly connected to the bottom of the pressure block, so that the pressure block has an elastic clamping force along the spring axis toward the positioning plane. An auxiliary guide rod is also fixed on the fixture body. The auxiliary guide rod is located on the left side of the spring mounting hole and is vertically fixed on the positioning plane for auxiliary positioning of the product.

[0011] In a preferred embodiment, the axis of the spring mounting hole is perpendicular to the positioning plane, and the spring is a stainless steel compression spring with a wire diameter of 0.4-0.6mm, a free length of 8-12mm, and a working stroke of 2-4mm, ensuring a clamping force of 5-10N on the product.

[0012] In a preferred embodiment, the pressure block has an arc-shaped pressing surface on the side facing the product. The curvature of the arc-shaped pressing surface is adapted to the curvature of the outer arc surface of the irregular arc structure product, so as to fit and press the product tightly and avoid damaging the product surface.

[0013] In a preferred embodiment, the fixture body is made of Cr12MoV alloy steel, and the positioning plane, positioning edge and auxiliary guide rod are all hardened to a hardness of HRC58-62. The outer circular surface of the auxiliary guide rod is precision ground to a surface roughness Ra≤0.4μm, straightness tolerance≤0.001mm, and perpendicularity tolerance≤0.001mm.

[0014] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are as follows: 1. Significantly reduced measurement error: Through the benchmark design of "high-precision positioning plane (flatness ≤ 0.002mm) + positioning edge (perpendicularity, straightness ≤ 0.001mm)", the 2D measuring instrument can directly take lines from the positioning edge, reducing the line taking error from 0.03mm to within 0.005mm, completely avoiding the problem of "measurement error accounting for 50% of the tolerance zone", and reducing the product misjudgment rate from 10% to below 0.1%.

[0015] 2. Significantly improved positioning efficiency: The auxiliary guide rod (left side positioning) and the positioning plane (reference plane) work together to achieve "one-click positioning" of the product - the operator only needs to align the left side of the product with the auxiliary guide rod and the reference plane with the positioning plane to complete the positioning. The time for a single positioning is reduced from 40-60 seconds to 5-8 seconds, and the measurement efficiency is improved by more than 80%.

[0016] 3. Comprehensive optimization of product protection: The arc-shaped pressing surface of the pressure block (curvature adaptation + low roughness) and the precisely controlled spring clamping force (5-10N) reduce the product surface damage rate from 5% to below 0.05%, while avoiding product deformation and ensuring product appearance and dimensional accuracy.

[0017] 4. Significantly improved jig durability: Made of Cr12MoV alloy steel with quenching treatment (HRC58-62), the jig achieves an accuracy decay of ≤0.002mm / year in high-frequency measurement scenarios with an average of more than 1,000 measurements per day. The calibration frequency is reduced from 2-3 times per month to once per quarter, and maintenance costs are reduced by 70%.

[0018] 5. Strong adaptability: By replacing pressure blocks with different curvatures (only the pressure blocks need to be replaced, and the fixture body does not need to be replaced), it can adapt to irregular arc products with curvature ranges of R1-R10mm, covering more than 90% of irregular arc small-sized products in the MIM industry. There is no need to design a separate fixture for a single product, reducing the equipment investment cost for enterprises. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Appendix Figure 1 This is a structural schematic diagram of the auxiliary fixture for measuring the dimensions of irregularly shaped arc-shaped products according to this utility model; Appendix Figure 2 An exploded view of the auxiliary fixture for measuring the dimensions of the irregular arc structure product of this utility model; The components include: 1. Fixture body; 2. Clamping assembly; 3. Positioning plane; 4. Positioning edge; 5. Pressure block; 6. Spring; 7. Spring mounting hole; 8. Auxiliary guide rod; 9. Irregular arc structure product. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the present invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1 Appendix Figure 1 and 2 The auxiliary fixture for measuring the dimensions of irregularly shaped arc-shaped products described in this utility model adopts an integrated structural design of "fixture body 1 + clamping component 2". The specific structure, connection relationship and performance parameters of each component are as follows: 1. Fixture body 1: High-precision positioning and durable foundation.

[0028] Material and overall structure: The fixture body 1 is made of Cr12MoV alloy steel (this material has high hardness and high wear resistance, and is suitable for high-frequency measurement scenarios in the MIM industry). The overall size is preferably 50mm long × 30mm wide × 10mm high (taking into account portability and stability), with no splicing gaps to avoid assembly errors.

[0029] Positioning plane 3: The top of the fixture body 1 is machined with a positioning plane 3 (preferably 35mm long × 25mm wide), which is precision ground by a surface grinder (grinding accuracy IT5 grade), with a flatness tolerance ≤0.002mm and a surface roughness Ra≤0.8μm; the positioning plane 3 serves as the bonding carrier for the product reference surface, ensuring that there is no gap between the product reference surface and the positioning plane 3 (gap ≤0.001mm), thus eliminating the reference offset error from the source.

[0030] Positioning edge 4: Along one edge of the positioning plane 3 (preferably the edge close to the line taking area of ​​the two-dimensional measuring instrument), the fixture body 1 is integrally formed with a positioning edge 4 (the length is the same as the length of the positioning plane 3, i.e., 35mm); the positioning edge 4 is set perpendicular to the positioning plane 3, with a perpendicularity tolerance ≤0.001mm and a straightness tolerance ≤0.001mm, which can be directly used as the reference line taking edge of the two-dimensional measuring instrument - replacing the small reference surface of the product, and completely solving the problem of "large line taking error".

[0031] Spring mounting hole 7: A spring mounting hole 7 (preferably 3mm in diameter and 8mm in depth) is provided on the fixture body 1 through its thickness direction. The axis of the spring mounting hole 7 is perpendicular to the positioning plane 3 (perpendicularity tolerance ≤0.001mm) for inserting the spring 6, ensuring that the direction of the force of the spring 6 is perpendicular to the positioning plane 3, and preventing the pressure block 5 from tilting.

[0032] Auxiliary guide rod 8: An auxiliary guide rod 8 is vertically fixed on the fixture body 1 (the distance between it and the spring mounting hole 7 is preferably 3-5mm to avoid interference with the spring 6), and it is clearly located on the left side of the spring mounting hole 7 (corresponding completely to the position of the small rod on the left in the exploded view); the auxiliary guide rod 8 is integrally formed with the fixture body 1 (without assembly gap), and its outer circular surface is precision ground (grinding accuracy IT4 grade), with a surface roughness Ra≤0.4μm, straightness tolerance≤0.001mm, and perpendicularity tolerance (relative to the positioning plane 3)≤0.001mm; the core function of the auxiliary guide rod 8 is to "assist in positioning the product" - by fitting against the left side of the product, it restricts the horizontal displacement (left and right direction) of the product along the positioning plane 3, while guiding the pressure block 5 to slide in the vertical direction to avoid the pressure block 5 from shifting.

[0033] Hardening treatment: The positioning plane 3, positioning edge 4 and auxiliary guide rod 8 are all subjected to overall quenching treatment (quenching process: 850℃ preheating → 1050℃ quenching → 200℃ tempering), and the quenching hardness reaches HRC58-62, ensuring surface wear resistance (service life can reach more than 500,000 times), and the accuracy decay after long-term use is ≤0.002mm / year, reducing the calibration frequency.

[0034] 2. Clamping component 2: Stable clamping and surface protection.

[0035] Spring 6: Spring 6 is a stainless steel compression spring (material 304 stainless steel, rust-proof and corrosion-resistant), with a wire diameter of 0.4-0.6mm (preferably 0.5mm), a free length of 8-12mm (preferably 10mm), and a working stroke of 2-4mm (preferably 3mm). Spring 6 is embedded in spring mounting hole 7, with one end abutting the bottom end face of spring mounting hole 7 (without looseness), and the other end fixedly connected to the bottom of pressure block 5 (using threaded connection, connection strength ≥50N, to prevent falling off). When working, spring 6 can provide a clamping force of 5-10N (preferably 8N), which can both press the product tightly against the positioning plane 3 (fitting gap ≤0.001mm) and prevent product deformation (deformation ≤0.0005mm).

[0036] Pressing block 5: Pressing block 5 is preferably made of POM material (polyoxymethylene, which has low friction and high toughness properties to avoid scratching the product), and its size is preferably 15mm long × 10mm wide × 8mm high; the side of pressing block 5 facing the product is processed with an arc-shaped pressing surface, and the curvature of the arc-shaped pressing surface is perfectly matched with the curvature of the outer arc surface of the irregular arc structure product 9 (for example, when the curvature of the outer arc surface of the product is R3mm, the curvature of the arc-shaped pressing surface is also R3mm, and the curvature tolerance is ≤0.001mm); the surface roughness Ra of the arc-shaped pressing surface is ≤0.4μm, which increases the contact area with the product (contact area ≥15mm²), avoids local pressure concentration, and completely eliminates the risk of scratching the product surface.

[0037] Sliding fit: The pressure block 5 has a guide hole at the position corresponding to the auxiliary guide rod 8 (the hole diameter is adapted to the diameter of the auxiliary guide rod 8, and the fit clearance is ≤0.005mm). The auxiliary guide rod 8 passes through the guide hole to ensure that the pressure block 5 slides smoothly along the axial direction of the auxiliary guide rod 8 (radial wobble ≤0.002mm). This further ensures that the clamping force of the spring 6 is always perpendicular to the positioning plane 3, and avoids the product not fitting tightly due to the offset of the pressure block 5.

[0038] Example 2 This application provides an auxiliary fixture for measuring the dimensions of irregularly shaped arc-shaped products, the specific structure of which is as follows: Fixture body 1: Made of Cr12MoV round steel (50mm in diameter), cut and milled, with overall dimensions of 50mm (length) × 30mm (width) × 10mm (height); locating plane 3 is ground using a precision surface grinder (model M7130) to achieve a flatness of 0.002mm and a surface roughness Ra=0.8μm; locating edge 4 is ground using a forming grinding wheel to achieve a perpendicularity of 0.001mm and a straightness of 0.001mm; spring mounting hole 7 is machined using a CNC drilling machine (model ZK3832) to achieve a hole diameter of... 3mm, depth 8mm, perpendicularity of axis to positioning plane 3 0.001mm; auxiliary guide rod 8 and fixture body 1 are integrally milled and then precision ground, diameter 2.5mm, length 14mm, outer surface roughness Ra=0.4mm, straightness 0.001mm, perpendicularity 0.001mm, top end is machined with R0.8mm rounded corner (to prevent scratches); finally, the whole thing is quenched (preheated at 850℃ for 30min → held at 1050℃ for 20min quenching → tempered at 200℃ for 2h), hardness HRC60.

[0039] Spring 6: 304 stainless steel compression spring 6, wire diameter 0.5mm, outer diameter 2.8mm (fits 3mm spring mounting hole 7), free length 10mm, working stroke 3mm, rated load 8N, elastic modulus 1.2N / mm, no rust after 24h salt spray test.

[0040] Pressing block 5: POM material injection molding followed by milling, dimensions 15mm long × 10mm wide × 8mm high; guide hole diameter 2.5mm, with a clearance of 0.003mm between it and auxiliary guide rod 8; arc-shaped pressing surface is machined by CNC milling machine (model XK7132), curvature R3mm (to match the outer arc surface of the target product), surface roughness Ra=0.4μm.

[0041] Its assembly steps: Insert the spring 6 into the spring mounting hole 7 from the top of the fixture body 1, ensuring that the lower end of the spring 6 is completely in contact with the bottom end face of the spring mounting hole 7 (without any gaps). Align the guide hole of the pressure block 5 with the auxiliary guide rod 8, and slide it downward along the axis of the auxiliary guide rod 8 until the upper end of the spring 6 contacts the bottom of the pressure block 5; Use an M2×3mm hex socket screw to connect the upper end of the spring 6 to the bottom of the pressure block 5 (screw screwed in to a depth of 2mm) to ensure that the spring 6 and the pressure block 5 are fixed without loosening. At this time, the pressure block 5 can slide freely along the auxiliary guide rod 8 (sliding resistance ≤0.5N).

[0042] Usage steps: Product Placement: The operator holds the pressure block 5 and pulls it upward (the spring 6 is compressed to a working stroke of 3mm, and the lifting resistance is about 8N). The irregular arc structure product 9 (dimensions 22.59×6.97×2.98mm, outer arc surface R3mm) is placed on the positioning plane 3, so that the reference surface of the product is in contact with the positioning plane 3, and the left side of the product is in close contact with the auxiliary guide rod 8 (the contact gap ≤0.001mm). Product clamping: Slowly release the pressure block 5, the spring 6 returns to its original position, and the pressure block 5 slides down along the auxiliary guide rod 8 until the arc-shaped pressing surface is completely in contact with the outer arc surface of the product. At this time, the spring 6 provides an 8N clamping force, and the product is stably fixed (without horizontal displacement or tilting). Dimensional measurement: Place the entire fixture on the worktable of the 2D measuring instrument (model VMS-2010), set the measurement coordinate system with the positioning edge 4 as the reference, start the measuring instrument to detect the target dimensions such as the length and radius of the arc of the product, and the measurement error is stable within 0.003-0.005mm; Product Removal: After measurement, pull up block 5 again to remove the product, and then proceed to the measurement process of the next product (single cycle time ≤ 15 seconds).

[0043] Finally, it should be noted that the above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An auxiliary fixture for measuring the dimensions of irregularly shaped arc-shaped products, characterized in that, Includes the fixture body and the clamping assembly; The top of the fixture body is provided with a positioning plane, which is precision machined by a grinding machine to ensure the flatness of the measurement reference. The fixture body is integrally formed with a positioning edge along the edge of the positioning plane. The positioning edge is set perpendicular to the positioning plane and is used as a reference line for two-dimensional measurement. The clamping assembly includes a pressure block and a spring. The spring is elastically connected between the fixture body and the pressure block. The side of the pressure block facing the positioning plane is used to fit against the irregular arc structure product. The elastic force of the spring presses the product against the positioning plane, so that the reference surface of the product fits tightly against the positioning plane, thereby achieving the positioning and fixing of the product.

2. The auxiliary fixture for measuring the dimensions of irregularly shaped arc structure products according to claim 1, characterized in that, The flatness tolerance of the positioning plane is ≤0.002mm, the perpendicularity tolerance of the positioning edge is ≤0.001mm, and the straightness tolerance of the positioning edge is ≤0.001mm.

3. The auxiliary fixture for measuring the dimensions of irregularly shaped arc structure products according to claim 1, characterized in that, The fixture body has a spring mounting hole that extends through its thickness direction. The spring is fitted into the spring mounting hole, with one end of the spring abutting the bottom end face of the spring mounting hole and the other end fixedly connected to the bottom of the pressure block, so that the pressure block has an elastic clamping force along the spring axis toward the positioning plane. An auxiliary guide rod is also fixed on the fixture body. The auxiliary guide rod is located on the left side of the spring mounting hole and is vertically fixed on the positioning plane for auxiliary positioning of the product.

4. The auxiliary fixture for measuring the dimensions of irregularly shaped arc structure products according to claim 3, characterized in that, The axis of the spring mounting hole is set perpendicular to the positioning plane. The spring is a stainless steel compression spring with a wire diameter of 0.4-0.6mm, a free length of 8-12mm, and a working stroke of 2-4mm, ensuring a clamping force of 5-10N on the product.

5. The auxiliary fixture for measuring the dimensions of irregularly shaped arc structure products according to claim 1, characterized in that, The pressure block has an arc-shaped pressing surface on the side facing the product. The curvature of the arc-shaped pressing surface is adapted to the curvature of the outer arc surface of the irregular arc structure product, which is used to fit and press the product tightly and avoid damaging the product surface.

6. The auxiliary fixture for measuring the dimensions of irregularly shaped arc structure products according to claim 1, characterized in that, The fixture body is made of Cr12MoV alloy steel. The positioning plane, positioning edge and auxiliary guide rod are all quenched and hardened to HRC58-62. The outer circular surface of the auxiliary guide rod is precision ground and has a surface roughness Ra≤0.4μm, straightness tolerance≤0.001mm and perpendicularity tolerance≤0.001mm.

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