Automobile part mounting plate sheet nut press rivet die

Abstract

The utility model discloses an automobile part mounting plate thin plate nut pressure riveting mould, including opposite arrangement's upper die subassembly and lower die subassembly, the lower die subassembly top is equipped with lower rivet female die fixed base, is embedded with lower rivet female die on lower rivet female die fixed base, the upper die subassembly bottom is equipped with upper rivet head fixed base, is installed with upper rivet head in upper rivet head fixed base bottom, upper rivet head bottom is equipped with the columnar convex part to the downwards, the convex part diameter is greater than the flanging outside diameter of riveting nut, the recess depth of lower rivet female die is greater than the flange height of riveting nut. The fixed geometric relation of convex part and recess depth is completed even stress in single stamping, and the pressure riveting efficiency is promoted and the equipment dependency is reduced, and simple structure does not need complicated control simultaneously, directly reduces the failure rate of mass production.

Description

Technical Field

[0001] This utility model relates to the field of automotive parts processing technology, and in particular to a die for pressing and riveting thin plate nuts on automotive parts mounting plates. Background Technology

[0002] In automotive parts manufacturing, the riveting process for thin-plate nuts on mounting plates directly affects assembly quality. Traditional tooling mainly employs two solutions: spin riveting equipment or simple riveting head dies. Spin riveting often results in insufficient torque resistance of the nuts due to uneven pressure transmission, especially on thin plates, easily causing deformation of the mounting plate. While simple riveting head dies offer higher pressure, their structure is not optimized for the flanged characteristics of the nuts, resulting in the nut end face 21 generally protruding above the mounting plate plane 20 after riveting. Figure 1 As shown, secondary grinding is required, increasing costs and potentially damaging the coating. Existing molds lack effective error prevention mechanisms; even when the nut is missing or misaligned, the riveting action continues, leading to increased product scrap rates. Some solutions using photoelectric sensors suffer from insufficient accuracy in nut center positioning due to installation position deviations. Furthermore, traditional pressure-bearing mechanisms rely on a single spring structure; long-term high-frequency stamping causes elastic decay, resulting in fluctuations in pressure force and affecting riveting consistency.

[0003] For example, the "Automotive Part Mounting Plate Thin Plate Nut Press-fitting Die" disclosed in Chinese patent literature, publication number "CN206912075U", includes an upper die core, which is divided into an mounting part and a punching part. The mounting part is installed in the upper core groove machined on the upper die. An elastic washer is provided on the outside of the punching part. A fixing block is provided at the lower end of the elastic washer. The fixing block and the elastic washer are fixed on the upper die by several sets of fixing bolts. The upper die is connected to the lower die through guide pillars. A lower core groove is machined on the lower die. A lower die core is provided inside the lower core groove. A press-fitting boss is machined at the bottom end of the upper die core. A press-fitting groove is machined at the top end of the lower die core corresponding to the position of the upper die core.

[0004] While the above solution eliminates the need for welding, drilling into components, and the purchase of any rivets, studs, or press-fit nuts for connection, completely overcoming the thermal deformation of workpieces caused by the high localized heat generated during welding of thin metal or non-ferrous metal sheets, it struggles to simultaneously meet three core requirements: ensuring the rear end face of the nut is perfectly flush with the mounting plate plane, maintaining stable torque resistance of the nut, and achieving zero missing riveting errors during production without requiring secondary processing. These challenges have become key bottlenecks restricting the improvement of the mass production pass rate of automotive parts. Utility Model Content

[0005] To address the problem of insufficient pressure in traditional riveting leading to nut detachment or uneven riveting requiring secondary grinding, this utility model provides a thin-plate nut riveting mold for automotive parts mounting plates. By optimizing the mold structure, a riveting effect is achieved where the nut end face is flush with the mounting plate plane and the torque meets the drawing requirements.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A riveting die for a mounting plate nut on an automotive part includes an upper die assembly and a lower die assembly arranged opposite each other. The lower die assembly has a lower riveting die fixing seat at its top, and a lower riveting die is embedded in the lower riveting die fixing seat. The upper die assembly has an upper riveting head fixing seat at its bottom, and an upper riveting head is installed at the bottom of the upper riveting head fixing seat. The bottom of the upper riveting head has a downward-facing columnar protrusion, the diameter of which is larger than the outer diameter of the flange of the riveting nut. The groove depth of the lower riveting die is greater than the flange height of the riveting nut.

[0008] This solution achieves precise riveting of nuts through the relative arrangement of upper and lower die components. The lower die component has a lower riveting die holder at the top that houses the lower riveting die, while the upper die component has an upper riveting head holder at the bottom that mounts the upper riveting head. The diameter of the columnar protrusion at the bottom of the upper riveting head is larger than the outer diameter of the flange of the riveted nut, and the depth of the groove in the lower riveting die is greater than the height of the nut flange. Traditional tooling, such as insufficient spin riveting pressure leading to nut detachment, or ordinary riveting heads requiring secondary grinding for uneven riveting, cannot meet the requirements of nut end face flush with the mounting plate and torque force. Specifically, the diameter of the protrusion of the upper riveting head is larger than the outer diameter of the nut flange, directly covering and flattening the nut flange area during stamping, avoiding uneven flange deformation; simultaneously, the depth of the groove in the lower riveting die is greater than the height of the nut flange, providing sufficient space to prevent flange overload and ensuring the nut maintains a stable position during riveting. This dimensional matching forces the nut flange to be completely pressed into the mounting plate hole through mechanical constraints, achieving end face flush with the plate surface and eliminating the need for secondary processing. Compared to common solutions, traditional methods rely on external pressure equipment, which can easily lead to pressure fluctuations, resulting in weak riveting or uneven surfaces. This solution, however, achieves uniform force distribution in a single stamping by using a fixed geometric relationship between the protrusion and the groove depth, improving riveting efficiency and reducing equipment dependence. At the same time, the simple structure eliminates the need for complex control, directly reducing the failure rate in mass production.

[0009] Therefore, this utility model has the following beneficial effects.

[0010] By using a structure where the diameter of the protruding part of the upper rivet head is larger than the outer diameter of the nut flange, the pressure is applied evenly to the circumference of the flange, making the end face of the nut flush with the plane of the mounting plate and eliminating the need for a secondary grinding process.

[0011] The design of the lower riveting die groove depth being greater than the nut flange height provides material flow space, avoids stress concentration, and ensures stable riveting force.

[0012] The layout of the electronic sensor protruding into the center of the groove, combined with the stepped positioning surface, enables dual verification of the nut position, reducing the failure rate of missing rivets to near zero.

[0013] The combination of nitrogen springs and flat wire springs, which are alternately distributed around the circumference of the pressure plate, maintains stable clamping force under high-frequency stamping, prevents deformation of thin plates, and extends the service life of the mechanism. Attached Figure Description

[0014] Figure 1 This is a structural diagram of a thin plate used for mounting automotive parts.

[0015] Figure 2 This is the front view of this utility model.

[0016] Figure 3 This is an isometric side view of the present invention.

[0017] Figure 4 yes Figure 1 Assembly structure diagram of the upper and middle rivets.

[0018] Figure 5 yes Figure 1 Axonometric view after the upper and middle rivets are assembled.

[0019] In the diagram: 01 Lower pad block, 02 Lower mold base, 03 Upper mold base, 04 Upper pad plate, 05 Pressure plate, 06 Product support block, 07 Nitrogen spring, 08 Flat wire spring, 09 Inner limit post, 10 Lower pad plate, 11 Outer limit post, 12 Lower riveting die fixing seat, 13 Die pad block, 14 Upper riveting head fixing seat, 15 Upper riveting head, 16 Lower riveting die, 17 Riveting nut, 18 Electronic sensor, 19 Electronic sensor fixing seat, 20 Mounting plate plane, 21 Nut end face. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1

[0022] like Figure 2-5 As shown, in this embodiment, a riveting mold for thin sheet nuts on automotive parts mounting plates is proposed, including an upper mold assembly and a lower mold assembly arranged opposite to each other; the lower mold assembly is provided with a lower riveting die fixing seat 12 at the top, and a lower riveting die 16 is embedded in the lower riveting die fixing seat 12; the upper mold assembly is provided with an upper riveting head fixing seat 14 at the bottom, and an upper riveting head 15 is installed at the bottom of the upper riveting head fixing seat 14; the bottom of the upper riveting head 15 is provided with a downward columnar protrusion, the diameter of which is larger than the outer diameter of the flange of the riveting nut 17; the groove depth of the lower riveting die 16 is larger than the flange height of the riveting nut 17.

[0023] The upper mold assembly also includes a pressure plate 05, which is located below the upper rivet head fixing seat 14 and has a through hole in the center for the upper rivet head 15 to pass through. An elastic clamping mechanism is provided between the pressure plate 05 and the main body of the upper mold assembly.

[0024] The elastic clamping mechanism includes a nitrogen spring 07 and a flat wire spring 08, which are alternately distributed along the circumference of the pressure plate 05. An electronic sensor mounting base 19 is provided on the side of the lower riveting die fixing base 12, and an electronic sensor 18 is mounted on the electronic sensor mounting base 19, protruding into the center of the groove of the lower riveting die 16. The inner wall of the groove of the lower riveting die 16 has a stepped positioning surface.

[0025] The lower mold assembly also includes a product support block 06 located around the lower riveting die fixing seat 12, with the top surface of the product support block 06 flush with the top surface of the lower riveting die 16.

[0026] The upper mold assembly includes an upper mold base 03 and an upper pad 04 connected sequentially from top to bottom, with an upper rivet head fixing seat 14 fixed to the bottom of the upper pad 04. A limiting post assembly is provided between the upper mold base 03 and the pressure plate 05, the limiting post assembly including an inner limiting post 09 located in the central area of ​​the pressure plate 05 and an outer limiting post 11 arranged around the inner limiting post 09.

[0027] In this embodiment, the automotive parts mounting plate nut riveting die achieves precise nut riveting through the structural cooperation of the upper and lower die assemblies. The lower riveting die holder at the top of the lower die assembly serves as the core support, with the lower riveting die embedded inside forming a groove structure to accommodate the nut. The groove depth is designed to be greater than the height of the nut flange, ensuring that the nut flange has sufficient deformation space without constraint during the riveting process. The upper riveting head holder at the bottom of the upper die assembly supports the upper riveting head. The diameter of the columnar protrusion extending from the bottom of the upper riveting head is greater than the outer diameter of the nut flange, allowing the protrusion to completely cover the nut flange area. When the press drives the upper die to press down, the protrusion of the upper riveting head first contacts the nut flange, while the depth allowance of the lower riveting die allows the nut flange to move downwards. Figure 1 As shown, the two work together to make the flange material extend evenly along the wall of the mounting plate hole, forming a riveting effect where the end face is flush with the plane of the mounting plate.

[0028] The pressure plate is fitted onto the outside of the upper riveting head through a through hole. The elastic clamping mechanism between the pressure plate and the upper die assembly body consists of nitrogen springs and flat wire springs arranged alternately in a circumferential pattern. The nitrogen springs provide a constant initial pressure, while the flat wire springs supplement high-frequency buffering. The combination of the two ensures that the pressure plate applies a stable clamping force to the mounting plate throughout the stamping process, preventing deformation of the thin plate. The inner and outer limit post groups set between the upper die base and the pressure plate form a dual stroke control: the inner limit post is located in the center area of ​​the pressure plate to limit the minimum clamping gap, and the outer limit post is distributed around it to prevent the pressure plate from tilting, together ensuring the consistency of the riveting depth.

[0029] The stepped positioning surface on the inner wall of the lower riveting die groove matches the outer contour of the nut, achieving self-positioning of the nut before riveting. An electronic sensor extends from the electronic sensor mounting base on the side of the lower riveting die fixing base; its detection end probes into the center of the groove to directly detect the presence of the nut, preventing missed riveting operations at the source. The top surface of the product support block surrounding the lower riveting die fixing base is flush with the top surface of the die, forming a complete bearing plane for the mounting plate, eliminating wrinkles in the sheet metal caused by localized suspension. The stacked connection structure of the upper die base and the upper pad disperses the punching torque, reducing stress concentration in the upper riveting head fixing base.

[0030] In the static structure, each component forms a functional unit through geometric constraints: the difference between the diameter of the upper riveting head protrusion and the dimensional difference between the nut flange and the diameter of the lower riveting die is greater than 0, forming a radial constraint; the difference between the depth of the lower riveting die and the height of the nut flange is greater than 0, forming an axial constraint. The physical boundary constructed together forces the flange material to flow in a preset direction. The coplanar setting of the product support block and the top surface of the die establishes a planar reference, and the stepped positioning surface provides circumferential limits. The three form a spatial coordinate system positioning system. The arrangement of the electronic sensor probing the center of the groove places the detection point at the geometric center of the nut, which reduces the misjudgment rate caused by positional deviations compared to peripheral detection.

[0031] Specifically, in this embodiment, the height of the columnar protrusion of the upper riveting head is set to 0.15mm. This dimension has been experimentally verified to completely flatten the nut flange without damaging the surface of the mounting plate. The protrusion is machined as a whole from hardened tool steel, and the end face is ground to Ra0.8μm surface finish to ensure uniform material flow during riveting. The depth of the lower riveting die groove is 0.5mm greater than the height of the nut flange. The diameter of the upper step of the stepped positioning surface on the inner wall of the die is clearance-fitted with the outer diameter of the nut, while the diameter of the lower step is smaller than the outer diameter of the nut flange but larger than the thread root diameter, forming an axial limiting structure. This design ensures that after the nut is placed, the bottom surface of the flange is 0.5mm away from the bottom of the groove, allowing the flange material to extend into this space during riveting, avoiding a surge in stress due to complete filling.

[0032] The diameter of the through hole in the pressure plate is 1.0-1.5mm larger than that of the upper riveting head rod, providing a centering adjustment margin for the riveting head. The alternating distribution of nitrogen springs and flat wire springs creates a composite stiffness characteristic, and the combination of the two keeps the pressure force constant in the middle of the stroke. The height of the inner limit post is 0.3mm lower than that of the outer limit post, forming a two-stage limiting mechanism—the outer limit post first contacts the pressure plate to limit the initial pressure position, and the inner limit post controls the pressing depth of the upper riveting head during the final riveting stage.

[0033] The product support block adopts a segmented layout. In this embodiment, four independent blocks are used, each with a width equal to half the hole spacing of the mounting plate. The surface of the support block is nitrided to a hardness of HV600. The horizontal distance between the probe end of the electronic sensor and the center of the groove is ≤2mm, directly detecting the center area of ​​the nut and avoiding edge misjudgment. The thickness of the upper pad is designed to be 1 / 3 of the mold base thickness, dispersing the impact pressure through gradient stiffness. A T-slot is machined at its bottom to fix the upper rivet head fixing seat. The groove depth and the flange height of the fixing seat are interference-fitted by 0.02mm to eliminate the risk of loosening under high-frequency impact.

[0034] Among them, the upper riveting head / lower riveting die is made of SKD11 high carbon high chromium steel with excellent wear resistance; the limit post assembly is made of SACM645 carburized steel with ideal impact resistance; this differentiated material configuration reduces manufacturing costs while ensuring overall rigidity.

[0035] The core of the component fit in this embodiment lies in the closed-loop control of the dimensional chain: the height of the upper riveting head protrusion is 0.15mm + the height tolerance of the inner limit post is ±0.01mm + the clearance of the through hole in the pressure plate is 0.05mm, and the cumulative error is controlled within ±0.1mm to ensure that the riveting depth accurately matches the deformation of the nut flange. The 0.5mm depth allowance of the lower riveting die complements the flatness tolerance of the product support block of ±0.02mm, preventing localized false pressure caused by uneven mounting plates.

[0036] In this embodiment, the riveting die operation begins with the positioning of the mounting plate: the operator places the mounting plate to be processed on the surface of the product support block of the lower die assembly, ensuring that the plate plane is completely flush with the top surface of the support block. At this time, the pre-punched hole on the mounting plate is aligned with the center of the lower riveting die. The riveting nut is placed into the groove manually or by a robot, and the nut flange is automatically centered due to the constraint of the stepped positioning surface. After the press is started, the upper die assembly moves downward as a whole, and the pressure plate contacts the surface of the mounting plate first. The nitrogen spring and the flat wire spring are compressed synchronously to generate a continuous clamping force, so that the thin plate is stably flush with the plane of the support block. As the upper die continues to move downward, the inner limit post contacts the upper surface of the pressure plate to form a primary stroke limit. At this time, the protruding part of the upper riveting head is about 0.5mm away from the flange of the nut.

[0037] Next comes the core stage: the upper riveting head fixing seat breaks through the initial limit and continues to press down, with the protrusion contacting the outer edge of the nut flange in a vertical direction. Under the action of the punch press tonnage, the design of the protrusion diameter being larger than the outer diameter of the flange ensures that the pressure is evenly applied to the entire flange circumference, forcing the flange material to extend radially along the wall of the mounting plate hole. At the same time, the nut flange moves slightly downward within the depth allowance space of the lower riveting die, and the 0.5mm gap reserved at the bottom of the groove accommodates material flow and avoids stress concentration. When the outer limit post contacts the pressure plate, the upper riveting head has just completed the final pressing amount of 0.15mm. At this time, the flange completely fills the gap of the mounting plate hole wall, and the nut end face is flush with the plate plane to ±0.05mm.

[0038] The electronic sensor performs a detection before the start of the stroke. If the nut is not placed or the offset exceeds the tolerance, the sensor probe will send a signal because no metal object is detected, and the press will brake urgently. The system will only allow the riveting action when the center of the nut coincides with the sensing axis. During the unloading stage, the upper die returns, and the rapid rebound characteristic of the flat wire spring causes the pressure plate to detach from the plate first, avoiding lifting the product. The riveted mounting plate is verified by a torque tester that the nut's torsional resistance is consistently above 40 N·m, and there are no indentations or deformations on the plate surface.

[0039] In practical production applications, this mold is compatible with 300-500kN punch presses and can complete 12-15 riveting operations per minute. The T-slot mounting structure of the upper riveting head fixing seat supports quick replacement of riveting heads of different diameters; when changing product specifications, only the positions of the lower riveting die and support block need to be adjusted simultaneously. The sealed design of the nitrogen spring ensures that the pressure force decreases by ≤3% after 100,000 stamping cycles, while the flat wire spring compensates for fatigue deformation through periodic pre-tightening. The direct-penetration layout of the electronic sensor controls the false detection rate to below 0.02%, improving accuracy by 20 times compared to traditional lateral detection solutions. During maintenance, the entire upper riveting head assembly can be removed by disassembling the upper pad fixing bolts, and replacement takes no more than 15 minutes.

[0040] Example 2

[0041] This embodiment improves upon the basic structure of Embodiment 1, focusing on enhancing heat dissipation efficiency, ease of product changeover, and adaptability to oily environments under high-frequency mass production conditions. An annular cooling water channel is added to the lower riveting die fixing seat, circulating cooling water to reduce the die's operating temperature and prevent lubricant carbonization due to high temperatures. The product support blocks are upgraded to an adjustable modular design, with a guide rail structure at the bottom of each support block. Radial position adjustment is achieved through lateral fasteners, eliminating the need to replace the entire support block assembly when adapting to different sized mounting plates.

[0042] The elastic clamping mechanism is replaced by a combination of hydraulic dampers and disc springs. The hydraulic dampers are symmetrically distributed at the four corners of the pressure plate and filled with hydraulic oil of appropriate viscosity. The disc spring assembly uses a multi-layered stacked form to provide non-linear clamping force. This combination maintains a more stable clamping force output during long-term stamping, reducing the impact of elastic decay on the flatness of the sheet metal. The limiting structure is simplified to a single-layer annular limiting ring. The inner wall of the integrally forged annular part maintains a clearance fit with the upper rivet head, and an array of heat dissipation holes is provided on the outer edge to reduce heat accumulation. Compared to the double-column limiting in Example 1, this reduces the cumulative error caused by the number of mating surfaces.

[0043] The electronic sensor incorporates an oil-resistant structure, with a metal protective sleeve extending from the sensor mount. An elastic seal is installed at the front end of the sleeve, and the sensor probe retracts into the sleeve to create physical isolation. The detection mode has been changed to directional signal transmission and reception, collecting only reflected signals within the cone-shaped area directly in front, effectively shielding against oil mist interference.

[0044] In the specific operation process, the product changeover process has been optimized: after adjusting the radial position of the support block to the new workstation, only the corresponding size of the lower riveting die needs to be replaced and the installation height of the limit ring adjusted. During stamping, the hydraulic damper absorbs the initial impact, and the disc spring provides incremental pressure at the end of the stroke, making the pressing process smoother. The single-point contact of the annular limit ring eliminates the risk of off-center loading, and the cooling system continuously suppresses the temperature rise of the die. The sensor's directional detection mode ignores splashing oil droplets, and a signal is triggered only when the nut fully enters the detection area.

[0045] This solution shortens product changeover time through adjustable support blocks, achieves zero false alarms in oily environments with directional anti-fouling sensors, and enhances pressure stability with a composite pressing mechanism. The cooling system and overall limiting ring work together to extend the lifespan of key components, significantly improving equipment reliability under harsh operating conditions while retaining the mechanical constraint advantages of Example 1.

Claims

1. A die for pressing and riveting thin sheet nuts on automotive parts mounting plates, comprising an upper die assembly and a lower die assembly disposed opposite to each other; characterized in that: The lower mold assembly is provided with a lower riveting die fixing seat (12) at the top, and a lower riveting die (16) is embedded in the lower riveting die fixing seat (12). The upper mold assembly is provided with an upper rivet head fixing seat (14) at the bottom, and an upper rivet head (15) is installed at the bottom of the upper rivet head fixing seat (14). The bottom of the upper rivet head (15) is provided with a downward columnar protrusion, the diameter of which is larger than the outer diameter of the flange of the rivet nut (17); The groove depth of the lower riveting die (16) is greater than the flange height of the riveting nut (17).

2. The riveting die according to claim 1, characterized in that: The upper mold assembly also includes a pressure plate (05), which is located below the upper rivet head fixing seat (14) and has a through hole in the center for the upper rivet head (15) to pass through. An elastic clamping mechanism is provided between the pressure plate (05) and the upper mold assembly body.

3. The riveting die according to claim 2, characterized in that: The elastic clamping mechanism includes a nitrogen spring (07) and a flat wire spring (08), which are alternately distributed along the circumference of the pressure plate (05).

4. The riveting die according to claim 1, characterized in that: An electronic sensor mounting base (19) is provided on the side of the lower riveting die fixing base (12), and an electronic sensor (18) is installed on the electronic sensor mounting base (19) and inserted into the center of the groove of the lower riveting die (16).

5. The riveting die according to claim 1, characterized in that: The inner wall of the groove of the lower riveting die (16) is provided with a stepped positioning surface.

6. The riveting die according to any one of claims 1-5, characterized in that: The lower mold assembly also includes a product support block (06) located around the lower riveting die fixing seat (12), the top surface of the product support block (06) being flush with the top surface of the lower riveting die (16).

7. The riveting die according to any one of claims 1-5, characterized in that: The upper mold assembly includes an upper mold base (03) and an upper pad (04) connected sequentially from top to bottom, and the upper rivet head fixing seat (14) is fixed to the bottom of the upper pad (04).

8. The riveting die according to claim 7, characterized in that: A set of limiting posts is provided between the upper mold base (03) and the pressure plate (05). The set of limiting posts includes an inner limiting post (09) located in the central area of ​​the pressure plate (05) and an outer limiting post (11) arranged around the inner limiting post (09).

Images