A kind of auxiliary tool for thread tapping on circular arc surface

Abstract

The utility model discloses a kind of for taping on arc surface Auxiliary tool and method, belong to the field of machining.The tool mainly includes with workpiece arc surface curvature matching tapping positioning plate, fixed assembly and tapping positioning pin.Tapping positioning plate is equipped with guide screw hole, and it is detachably fixed on workpiece by fixed assembly.When using, tapping positioning pin is rotated into guide screw hole and inserts pre-processed thread bottom hole simultaneously, realizes accurate positioning, makes guide screw hole and bottom hole coaxial;Subsequently, fixed assembly is fastened, and positioning plate is clamped firmly on workpiece;After positioning pin is removed, tapping can be carried out by guide screw hole using tap.The utility model is guided by machine and is forcedly positioned, effectively ensures that tap tapping direction is always along arc surface normal, completely solves the technical problem that manual tapping is easy to deflect, guarantees that thread hole center line passes through arc center, simple structure, convenient operation, and strong universality.

Description

Technical Field

[0001] This utility model relates to the field of machining technology, specifically to an auxiliary tool for tapping on arc surfaces. Background Technology

[0002] In the field of machining, it is common to encounter situations where threaded holes need to be machined on the curved outer surface of parts such as cylinders and arc supports. Such operations, especially when manually tapping on the production site, face a long-standing technical problem that has not been effectively solved: the initial guidance and feed direction of the tap are difficult to control, and deviation is very likely to occur.

[0003] Because a circular arc surface is a three-dimensional curved surface, it is difficult for the operator to accurately ensure, by sight and touch, that the tap axis is perpendicular to the tangent plane of the arc surface, i.e., to ensure that it passes through the center point (normal direction) of the arc section. At the moment the tap enters the material, if the force is uneven, it will slide along the tangent of the arc, causing the axis of the threaded hole to become misaligned. This misalignment can lead to a series of serious consequences: incomplete thread profile and significantly reduced strength; screws cannot be screwed in or tightened properly; additional bending moments are generated under load, accelerating thread failure; and even the tap may break during tapping, rendering the workpiece unusable.

[0004] Currently, solutions to this problem are very limited. For factories with the resources, high-precision CNC machining centers or dedicated tapping equipment can be used, with angles controlled by a program. However, this requires significant investment and lengthy programming preparation time, making it unsuitable for single-piece or small-batch production or on-site repair. Another approach is to manufacture dedicated drilling jigs or tapping fixtures. However, these tooling fixtures are typically designed for specific parts and lack versatility. When product models change or the curvature of the arc changes, the existing tooling becomes ineffective, requiring redesign and remanufacturing, which is costly, time-consuming, and extremely inconvenient to manage.

[0005] Therefore, there is an urgent need in this field for a universal auxiliary tool that can be applied to arc surfaces of different curvatures, is easy to operate, is inexpensive, and can effectively prevent hand tapping from deviating, in order to fill the gap in the existing technology and improve the quality and efficiency of such processing steps. Utility Model Content

[0006] This utility model aims to overcome the shortcomings of the prior art and provide an auxiliary tool for tapping on arc surfaces, comprising: A tapping positioning plate, having an arc surface that matches the workpiece to be machined, and having at least one guide thread hole thereon; and The fixing component allows the tapping positioning plate to be detachably fixed to the workpiece to be processed. The fixing component can also adjust the position of the positioning plate relative to the workpiece to be processed, so that the guide thread hole is coaxial with the pre-machined thread bottom hole on the arc surface.

[0007] Furthermore, the tapping positioning plate is provided with two bosses, making the cross-section of the tapping positioning plate concave, for clamping the workpiece to be processed. The fixing assembly includes at least one positioning screw, which is installed in the bolt hole of the boss and abuts against the side surface of the arc surface through its end to restrict the circumferential movement of the tapping positioning plate.

[0008] Furthermore, a fixing plate is included, which is detachably mounted on one or both sides of the tapping positioning plate by fixing screws to form a boss.

[0009] Furthermore, the gap between the fixing plate and the tapping positioning plate is adjusted by fixing screws to accommodate the arc surface of the workpiece with different widths.

[0010] Furthermore, this also includes tapping locating pins; The upper section of the tapping locating pin has an external thread for engaging with the threaded guide hole; the lower section of the tapping locating pin is a locating cylinder for inserting into the threaded bottom hole to achieve the initial precise positioning of the tapping locating plate.

[0011] Furthermore, the tool includes a set of tapping locating pins with different lengths and diameters, and tapping locating plates with different diameters for guiding threaded holes, to accommodate threaded holes on different arc surfaces to be machined.

[0012] Furthermore, a buffer layer is provided at the end of the positioning screw.

[0013] Furthermore, the tool includes a set of tapping positioning plates with different curvatures and each equipped with a guide thread hole to accommodate the arc surfaces to be machined with different radii of curvature.

[0014] Furthermore, the guide thread hole is a wear-resistant bushing embedded in the tapping positioning plate, and the internal thread of the wear-resistant bushing is consistent with the specifications of the guide thread hole.

[0015] Furthermore, the concave positioning surface of the tapping positioning plate and the end face of the boss that contacts the workpiece are provided with textures to increase friction or with shims.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: The auxiliary tool and process method for tapping on arc surfaces provided by this utility model have the following significant advantages compared with the prior art: The core advantage of this invention lies in eliminating the possibility of tap deflection when manually tapping on a curved surface. By designing a tapping positioning plate that precisely matches the workpiece curvature and its guiding thread hole, a rigid guiding path is established for the tap, perfectly aligned with the normal direction of the curved surface. The tap is confined to this path throughout the tapping process, thus ensuring that the centerline of the final machined threaded hole passes through the center point of the curved surface. This mechanical, forced guidance overcomes the uncertainty and instability inherent in relying solely on the operator's feel and experience, resulting in a significant leap in machining accuracy.

[0017] Adaptable to different curvatures: By being equipped with a set of tapping positioning plates with different curvatures, this tool can be used for workpieces with curved surfaces of various radii of curvature.

[0018] Adaptable to different workpiece sizes: With adjustable length fixing screws and replaceable fixing plates, the tool can stably clamp workpieces of different widths.

[0019] Adaptable to different thread specifications: Different sizes of guide thread holes can be set on a single positioning plate, or the entire positioning plate can be replaced to meet the tapping requirements of various threads such as M6 and M8.

[0020] This design transforms the tool from a "dedicated tooling" into a "general-purpose platform," greatly expanding its application scenarios and reducing the cost for users to repeatedly manufacture tooling for different products.

[0021] The tool's operation is clear and simple. Rapid initial positioning is achieved using the tapping locating pin, eliminating the need for repeated measurements and adjustments. The clamping mechanism is intuitively designed and easy to assemble and disassemble. Throughout the process, operators do not need extremely high skill levels or extensive experience to consistently produce high-quality threaded holes. This not only reduces reliance on highly skilled technicians and decreases scrap rates caused by human error, but also significantly improves production efficiency, making it particularly suitable for small-batch, multi-variety production and on-site maintenance operations.

[0022] All components of this invention can be manufactured using conventional machining methods, requiring no complex electronic equipment or precision sensors. It features a simple structure, robust durability, and low failure rate. Its manufacturing cost is significantly lower than that of automated equipment such as CNC machine tools. Maintenance is convenient, and its lifespan is long (especially with the adoption of wear-resistant bushings). This makes this tool highly suitable for widespread adoption in small and medium-sized enterprises, workshops, and repair sites, offering significant economic and practical value. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a cross-sectional view of the present invention in use. Figure 3 This is an exploded view of this utility model; Figure 4 This is a schematic diagram of the structure of the workpiece to be processed according to this utility model.

[0024] Marked in the image: 1-Tapping positioning plate, 2-Fixing plate, 3-Tapping positioning pin, 4-Positioning screw, 5-Fixing screw, 6-Workpiece to be processed, 7-Guiding thread hole, 8-Thread bottom hole, 9-Boss. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings.

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0027] In this embodiment, as Figure 1-4 As shown, an auxiliary tool for tapping on a curved surface includes: The tapping positioning plate 1 is set as an arc surface that matches the workpiece 6 to be processed, and has at least one guide thread hole 7 on it; The tapping positioning plate 1 can be detachably fixed to the arc surface of the workpiece 6 to be processed by the fixing component, and the guide thread hole 7 is coaxial with the pre-machined thread bottom hole 8 on the arc surface.

[0028] In the core embodiment of this utility model, the auxiliary tool includes a core component: a tapping positioning plate 1. This positioning plate is pre-machined into an inner arc surface that matches the outer arc surface of the workpiece 6 to be processed, ensuring a full fit between the two. At least one guide threaded hole 7 is machined on the positioning plate. The axis of this hole is designed to automatically remain coaxial with the pre-machined threaded bottom hole 8 on the arc surface after it is fitted with the arc surface. A fixing assembly is used to temporarily fasten the aligned tapping positioning plate 1 to the workpiece. Its working principle is: using the positioning plate, which matches the curvature of the arc surface, as a reference, the precise spatial position (normal direction) of the guide threaded hole 7 is transmitted to the workpiece. The beneficial effect is that it fundamentally establishes a rigid guide path for the tap that is consistent with the normal direction of the arc surface, solving the problem of skewing that inevitably occurs during hand tapping due to the lack of guidance.

[0029] Furthermore, the tapping positioning plate 1 is provided with two bosses 9, making the cross section of the tapping positioning plate 1 concave, for clamping the workpiece 6 to be processed. The bosses 9 are provided with bolt holes, and the fixing assembly includes at least one positioning screw 4. The positioning screw 4 is installed in the bolt hole of the boss 9 and abuts against the side surface of the arc surface through its end to restrict the circumferential movement of the tapping positioning plate 1.

[0030] To further optimize clamping stability, the tapping positioning plate 1 is designed with two bosses 9, one above the other, giving it a concave cross-section. This concave structure can straddle the arc surface of the workpiece like a caliper. Bolt holes are machined on the bosses 9. The positioning screws 4 in the fixing assembly are screwed into these holes. When tightened, the end of the screw presses firmly against the side surface (end face) of the arc surface. The axial tightening force of the positioning screws 4 generates a large static friction force on the side surface of the workpiece. This friction force is sufficient to resist the circumferential torsional torque generated by the tap rotation during tapping, preventing the entire positioning plate from rotating. This effectively constrains the circumferential degree of freedom of the positioning plate, and this constraint method does not damage the workpiece body and is convenient for assembly and disassembly.

[0031] Furthermore, including fixing, 2, the fixing plate 2 is detachably set on one or both sides of the tapping positioning plate 1 by fixing screws 5 to form a boss.

[0032] To enhance the tool's adaptability to workpieces of varying thicknesses, a fixing plate 2 is introduced into the fixing assembly. This fixing plate 2 is detachably mounted on one or both sides of the tapping positioning plate 1 using fixing screws 5. When mounted on both sides, they, together with the positioning plate body, form a "boss 9". Its working principle is to transform the originally integral, fixed-thickness boss 9 into a detachable and replaceable module. By selecting fixing plates 2 of different sizes, the width of the "concave" groove can be flexibly adjusted. The beneficial effect is a significant improvement in the tool's versatility; a single tool can handle various workpieces of different thicknesses by replacing only a few parts, reducing manufacturing and usage costs. In this embodiment, one side of the boss 9 is set using a fixing plate 2, while the other side uses an integrally formed boss 9.

[0033] Specifically, such as Figure 1 , 3As shown, one end of the tapping positioning plate 1 is configured as a fixed boss, and the other end is fitted with a fixing plate 2 via a fixing screw 5. Thus, the fixed boss of the tapping positioning plate 1 and the fixing plate 2 together form a clamping structure with an approximately "concave" cross-section, used to hold the workpiece 6 to be processed from both sides. Bolt holes are machined on both the fixed boss and the fixing plate 2, into which the positioning screw 4 is screwed. When the positioning screw 4 is tightened, its end radially presses against the side surface of the workpiece's arc surface, using the resulting large static friction force to restrict the circumferential movement of the tapping positioning plate 1. The gap between the fixing plate 2 and the tapping positioning plate 1 is adjusted by the fixing screw 5 to accommodate workpiece arc surfaces of different widths.

[0034] Specifically, a fixing plate 2 is detachably mounted on the mounting part of the tapping positioning plate 1 using fixing screws 5. The fixing screws 5 engage with threaded holes on the tapping positioning plate 1; by screwing them in or out, the relative distance between the fixing plate 2 and the fixing boss of the tapping positioning plate 1 can be precisely adjusted, thereby achieving fine-tuning of the clamping gap for workpieces of different thicknesses. Thus, the fixing boss of the tapping positioning plate 1 and the adjustable fixing plate 2 together constitute a clamping structure with adjustable clamping width, used to adaptively grip the workpiece 6 to be processed from both sides.

[0035] Furthermore, it also includes tapping locating pin 3; The upper section of the tapping positioning pin 3 is provided with external threads for threaded engagement with the guide threaded hole 7; the lower section of the tapping positioning pin 3 is a positioning cylinder for insertion into the threaded bottom hole 8 to achieve initial precise positioning of the tapping positioning plate 1.

[0036] To achieve rapid and accurate initial positioning of the tapping positioning plate 1, a tapping positioning pin 3 is added to the tool. This positioning pin adopts a composite design with an upper external thread and a lower positioning cylinder. Its working process is as follows: first, the positioning pin is screwed into the guide threaded hole 7 of the tapping positioning plate 1; then, the lower positioning cylinder is inserted into the pre-machined threaded bottom hole 8 on the workpiece. During this process, the precise fit between the positioning cylinder and the bottom hole forcibly "pulls" the tapping positioning plate 1 to the correct spatial position, making its guide threaded hole 7 coaxial with the bottom hole of the workpiece. After positioning is completed, the positioning pin is unscrewed. This achieves high-precision positioning, is simple and reliable to operate, and avoids errors that may occur during manual visual alignment.

[0037] Furthermore, the tool includes a set of tapping locating pins 3 with different lengths and diameters to accommodate threaded holes on different arc surfaces to be machined.

[0038] To handle threaded holes 8 of varying depths and diameters, the tool is equipped with a set of tapping locating pins 3 of different lengths and diameters. The principle behind this design is that the diameter of the locating cylinder must achieve a clearance fit with the diameter of the threaded hole 8, and its length must be sufficient to effectively insert into the hole to ensure stable positioning. Therefore, for different threaded hole specifications (such as M6, M8, etc.), locating pins of corresponding diameters are required; for holes of different depths or special structures, locating pins of different lengths are required. The beneficial effect is that it expands the application range of the locating pin principle, enabling this high-precision positioning method to cover various processing needs.

[0039] Furthermore, a buffer layer is provided at the end of the positioning screw 4.

[0040] To prevent the positioning screw 4 from causing indentations or scratches on the side surface of the precision workpiece, a buffer layer is provided at the end of the positioning screw 4. This buffer layer can be an embedded copper head, a nylon head, or a coated elastic material. When the screw tightens on the workpiece, the soft buffer layer undergoes elastic deformation, increasing the contact area and evenly distributing the strong tightening force, thus preventing stress concentration and crushing of the workpiece surface by the hard metal screw head. Without sacrificing clamping force, it protects the surface quality of the workpiece, making it particularly suitable for precision-machined workpieces or workpieces with strict surface requirements.

[0041] Furthermore, the tool includes a set of tapping positioning plates 1 with different curvatures and each equipped with guide thread holes 7, to accommodate the arc surfaces to be machined with different radii of curvature.

[0042] To address the challenges of curved surfaces with varying radii of curvature, this utility model provides a kit containing a series of tapping locating plates 1 with different curvatures. Each locating plate has a fixed inner curvature radius that matches the specific workpiece's radius. Users simply select the plate with the closest curvature from the kit. The advantage is that it transforms a customized tooling into a universal platform system, covering a wide range of curved surface tapping needs by providing a limited number of standard curvature locating plates.

[0043] Furthermore, the guide thread hole 7 is a wear-resistant bushing embedded in the tapping positioning plate 1, and the internal thread of the wear-resistant bushing is consistent with the specifications of the guide thread hole 7.

[0044] Considering that the accuracy of the guide threaded hole 7 will decrease due to tap wear after long-term use, the guide threaded hole 7 is designed to consist of an independent wear-resistant bushing (such as a high-carbon steel bushing or a wire thread insert), which is embedded in the base of the tapping positioning plate 1 with an interference fit. This separates the vulnerable part (internal thread) from the main structure (positioning plate). The wear-resistant bushing is made of a harder and more wear-resistant material, with a lifespan far exceeding that of threads tapped directly on the positioning plate. When the bushing eventually wears out, it can be pressed out and replaced with a new one. This significantly extends the service life of the entire tool set, reduces long-term maintenance costs, and ensures the stability of long-term machining accuracy.

[0045] Furthermore, the concave positioning surface of the tapping positioning plate 1 and the end face of the boss 9 that contacts the workpiece are provided with textures to increase friction or with shims.

[0046] To further increase friction on the clamping surfaces and prevent minor axial slippage, textures (such as knurling) or shims are applied to the concave locating surface of the tapping locating plate 1 (the surface in contact with the outer arc of the workpiece) and the contact end surface between the boss 9 and the side of the workpiece. The rough texture or the high-friction shims significantly increase the coefficient of friction between the tool and the workpiece interface. Using the same screw tightening force, stronger anti-slip and anti-rotation capabilities are achieved, further improving the stability and reliability of the tapping process.

[0047] The specific usage process is as follows: S1: Based on the radius of curvature of the workpiece 6 to be processed, select a matching piece from a set of tapping positioning plates 1 with different curvatures.

[0048] Based on the specifications of the thread to be tapped (such as M6, M8), confirm that the specifications of the guide thread hole 7 on the positioning plate are correct.

[0049] Based on the diameter and depth of the pre-machined threaded bottom hole 8 on the workpiece, select a locating pin with a matching diameter and appropriate length from a set of tapping locating pins 3 of different specifications.

[0050] S2: Place the selected tapping positioning plate 1 with its inner arc surface against the arc surface of the workpiece.

[0051] Screw the upper external thread of the selected tapping locating pin 3 into the guide thread hole 7 of the locating plate, and then gently insert the lower locating cylinder into the pre-machined threaded bottom hole 8 on the workpiece. This step forces the guide thread hole 7 and the threaded bottom hole 8 to achieve precise coaxiality.

[0052] S3: Select a suitable fixing plate 2 according to the width of the workpiece, and install it on one or both sides of the tapping positioning plate 1 by means of adjustable length fixing screws 5 to form a "concave" shaped clamping structure.

[0053] Screw the positioning screw 4 into the bolt hole of the boss 9 on the tapping positioning plate 1 (and the fixing plate 2). Gradually tighten the positioning screw 4 using a tool until its end is firmly against the side surface of the workpiece's arc surface. At the same time, ensure that the fixing plate 2 is also in contact with the other side of the workpiece, thereby firmly clamping the entire tool onto the workpiece.

[0054] S4: After confirming that the tapping positioning plate 1 is completely fixed and there is no looseness, unscrew it in the opposite direction and remove the tapping positioning pin 3.

[0055] Insert the guide end of the tap into the guide thread hole 7 of the tapping positioning plate 1 to ensure a good fit between the tap and the hole. At this point, the axis of the tap has been precisely guided to be aligned with the normal direction of the arc surface.

[0056] Begin manually rotating the tap to tap. During the tapping process, the guide thread hole 7 will strictly constrain the path of the tap to prevent it from deviating, thereby producing a threaded hole with its center line passing through the center of the arc.

[0057] S5: After tapping is completed, reverse the tap to remove it from the threaded hole and the guide threaded hole 7.

[0058] Loosen the positioning screw 4 in sequence, remove the fixing screw 5 and the fixing plate 2, and the entire auxiliary tool can be removed from the workpiece.

[0059] Clean up tools and work area, and complete all operations.

[0060] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the utility model should be included within the protection scope of the utility model.

Claims

1. An auxiliary tool for tapping on arc surfaces, characterized in that, include: The tapping positioning plate (1) is provided with an arc surface that matches the workpiece (6) to be processed, and at least one guide thread hole (7) is provided on it. as well as The fixing component allows the tapping positioning plate (1) to be detachably fixed to the workpiece (6) to be processed, and the fixing component can adjust the position of the positioning plate (1) relative to the workpiece to be processed so that the guide thread hole (7) is coaxial with the pre-machined thread bottom hole (8) on the arc surface.

2. The auxiliary tool for tapping on an arc surface according to claim 1, characterized in that, The tapping positioning plate (1) is provided with two bosses (9), making the cross section of the tapping positioning plate (1) concave, for clamping the workpiece (6) to be processed. The fixing component includes at least one positioning screw (4), which is installed in the bolt hole of the boss (9) and abuts against the side surface of the arc surface through its end to restrict the circumferential movement of the tapping positioning plate (1).

3. The auxiliary tool for tapping on an arc surface according to claim 2, characterized in that, Includes a fixing plate (2), which is detachably mounted on one or both sides of the tapping positioning plate (1) by fixing screws (5) to form the boss (9).

4. The auxiliary tool for tapping on an arc surface according to claim 3, characterized in that, The gap between the fixing plate (2) and the tapping positioning plate (1) is adjusted by fixing screws (5) to accommodate the arc surface of the workpiece (6) with different widths.

5. The auxiliary tool for tapping on an arc surface according to any one of claims 1-4, characterized in that, It also includes tapping locating pins (3); The upper section of the tapping positioning pin (3) is provided with an external thread for thread engagement with the guide threaded hole (7); the lower section of the tapping positioning pin (3) is a positioning cylinder for insertion into the threaded bottom hole (8) to achieve the initial precise positioning of the tapping positioning plate (1).

6. The auxiliary tool for tapping on an arc surface according to claim 5, characterized in that, The tool includes a set of tapping positioning pins (3) with different lengths and diameters and tapping positioning plates (1) with different diameter guide thread holes (7) to accommodate threaded holes on different arc surfaces to be machined.

7. The auxiliary tool for tapping on an arc surface according to any one of claims 1-4, characterized in that, The end of the positioning screw (4) is provided with a buffer layer.

8. The auxiliary tool for tapping on an arc surface according to any one of claims 1-4, characterized in that, The tool includes a set of tapping positioning plates (1) with different curvatures and each having the guide thread hole (7) to adapt to the arc surfaces to be processed with different radii of curvature.

9. The auxiliary tool for tapping on an arc surface according to any one of claims 1-4, characterized in that, The guide thread hole (7) is a wear-resistant bushing embedded in the tapping positioning plate (1), and the internal thread of the wear-resistant bushing is consistent with the specifications of the guide thread hole (7).

10. The auxiliary tool for tapping on an arc surface according to claim 2, characterized in that, The concave positioning surface of the tapping positioning plate (1) and the end face of the boss (9) that contacts the workpiece are provided with textures to increase friction or with pads.

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