Precise medical instrument punch forming system and method based on controllable tearing process

Abstract

The invention discloses a precise medical instrument punch forming system and method based on a controllable tearing process. The system comprises a lower supporting plate, the lower supporting plate is connected with a lower die base through lower foot pads, a lower base plate is arranged on the lower die base, a lower die plate is arranged on the lower base plate, and a material plate is arranged on the lower die plate; the material plate, the lower die plate and the lower base plate are connected with the lower die base through two first floating guide pins. A lower limiting column, a lower die knife edge, a forming insert, a stripping block and an inner limiting column are arranged in the lower die plate. The lower die base is connected with an upper die base through an outer guide column, and the upper die base is sequentially connected with an upper padding plate, an upper clamping plate, a stop plate and a stripper plate through an inner guide column. The aligned round holes of the upper clamping plate, the stop plate and the stripper plate are connected with a forming punch and a punching punch. The material utilization rate is improved, and the cost is reduced; the method is suitable for various materials and thickness ranges, and the process universality is high; and the torn product is stable in performance and high in surface quality, and meets the high-precision requirement of medical instruments.

Description

Technical Field

[0001] The invention belongs to the technical field of sheet metal stamping manufacturing, and relates to a precision medical device stamping and forming system and method based on a controllable tearing process. Background Art

[0002] Precision components of medical devices usually require high precision, high strength and surface quality. In the traditional stamping process, burrs, deformation or cracks are easily generated during the tearing process, affecting the product performance and service life. The existing tearing process has a low material utilization rate and high cost. Aiming at the special requirements of precision medical device components, the existing process is difficult to meet the needs of high precision and high reliability. The traditional stamping process has the following technical problems when processing thin sheets of medical stainless steel (such as 316L) and titanium alloy (such as Ti6Al4V) with a thickness ≤ 0.3 mm: 1. Dimension deviation caused by edge wear: After continuous stamping 10,000 times, the tool clearance expands by 0.05 - 0.08 mm. 2. Excessive burr height: The burr height generated by conventional stamping reaches 0.03 - 0.05 mm, and an additional deburring process is required. 3. Low material utilization rate: The scrap rate of complex contour machining is as high as 35 - 40%. 4. Microstructural damage: The depth of the grain deformation layer of the blanking section reaches 20 - 30 μm. Summary of the Invention

[0003] The invention provides a precision medical device stamping and forming system and method based on a controllable tearing process, which is applicable to the manufacture of precision components of medical devices, and a tearing process that can improve tearing precision, reduce residual stress and ensure product stability.

[0004] To solve the above problems, the technical solutions provided by the invention are as follows:

[0005] An embodiment of the present invention provides a precision medical device stamping and forming system based on a controllable tearing process, including a lower support plate (1), the lower support plate (1) is connected to a lower die base (3) through lower foot pads (2), a lower backing plate (4) is arranged on the lower die base (3), a lower template (5) is arranged on the lower backing plate (4), a blanking plate (6) is arranged on the lower template (5), the blanking plate (6), the lower template (5) and the lower backing plate (4) are connected to the lower die base (3) through two first lifting and guiding pins (7), and a lower limit post (12), a lower die cutting edge (8), a forming insert (9), a stripper block (10) and an inner limit post (11) are arranged in the lower template (5); the lower die base (3) is connected to an upper die base (14) through an outer guide post (13), and the upper die base (14) is sequentially connected with an upper backing plate (15), an upper clamping plate (16), a stop plate (17) and a stripper plate (18) through an inner guide post (21); round holes aligned with the upper clamping plate (16), the stop plate (17) and the stripper plate (18) are connected with a forming punch (21) and a punching punch (22), and hooks (19) are connected to the sides of the upper backing plate (15), the upper clamping plate (16), the stop plate (17) and the stripper plate (18).

[0006] In a preferred embodiment of the present invention, a lower limit post (12) is further arranged at the end of the lower die base (3).

[0007] In a preferred embodiment of the present invention, an upper limit post (20) is further arranged at the end of the upper die base (14), and the upper die base (14) is also connected to the upper backing plate (15) and the upper clamping plate (16) through a second lifting and guiding pin (24).

[0008] In a preferred embodiment of the present invention, the upper die base (14) is prepared by using a polycrystalline diamond coating, and its surface roughness Ra ≤ 0.05 μm; the lower die base (3) is a multi-stage buffer structure with a silica gel layer and a disc spring group, and its elastic modulus gradient distribution is 0.5 - 5 GPa.

[0009] In a preferred embodiment of the present invention, the punching punch (22) adopts a conical or stepped punch to reduce stress concentration.

[0010] An embodiment of the present invention also provides a precision medical device stamping and forming system and method based on a controllable tearing process, which is realized by using a precision medical device stamping and forming system based on a controllable tearing process as described in the above embodiment, and is characterized in that it includes the following steps:

[0011] Step 1, Weakening Structure Design: a) Pre-set micron-level grooves along the target contour line, with a depth of 30 - 50 μm and a width of 50 - 80 μm; b) Use picosecond laser processing, with a heat-affected zone < 5 μm; c) Groove angle control: Incline at 75° ± 2° along the optimized tearing direction with respect to the plate plane;

[0012] Step 2, Dynamic Load Control: a) Initial stage: Maintain a pre-tightening force of 500 - 800 N for 0.5 - 1.0 s to eliminate material springback; b) Tearing stage: Stepwise loading, with a peak pressure of 2000 ± 50 N and a loading rate of 50 N / ms; c) Real-time feedback from a pressure sensor, with an accuracy of ±1.5%, and use the measured data of HBMU9C type sensor;

[0013] Step 3, Composite Die Structure: a) Control the gap between the blanking plate and the stripper plate within 0.01 - 0.03 mm to ensure tearing accuracy; Stamping parameter optimization: a) Control the punch speed within 50 - 100 mm / s to avoid excessive impact causing workpiece deformation; Adjust the stamping pressure range to 10 - 50 MPa according to the thickness and material strength of the sheet metal part; Optimize the tearing force through finite element simulation, and control the tearing force within 1.2 - 1.5 times the yield strength of the material; Adopt preloading technology to reduce the springback of the sheet metal part after tearing, with the springback controlled within 0.02 mm.

[0014] A preferred embodiment of the present invention includes: Step 4, Lubrication and Cooling: Lubricant: Use a water-based lubricant with a concentration of 2% - 5% to reduce friction and die wear. Cooling system: Adopt circulating cooling water, with the temperature controlled within 20 - 30 °C to avoid performance degradation caused by overheating of the material; Tearing process: Multi-stage tearing: Gradually complete the separation of the sheet metal part through multi-stage dies to reduce the stress of single tearing; Precision control: Control the dimensional tolerance of the sheet metal part after tearing within ±0.02 mm, and the surface roughness Ra ≤ 1.6 μm.

[0015] A preferred embodiment of the present invention includes: Step 5, Material Selection and Pretreatment: Applicable materials: Applicable to 304 stainless steel, 420 stainless steel, and low-carbon steel, with a material thickness range of 0.2 - 2 mm; Surface pretreatment: The surface of the workpiece needs to be sandblasted, with a roughness Ra ≤ 1.6 μm to improve the biting force during tearing.

[0016] A preferred embodiment of the present invention includes: Step 6, mold design: The surface of the mold cavity needs to be hardened, and the surface roughness is controlled at Ra0.4 - 0.8μm; Tear slots are pre-designed on the sheet metal part, with a slot width of 0.5mm and a depth of 1 / 2 of the sheet metal thickness; Equipment and process parameters: Press parameters: A hydraulic press is selected, with a punch stroke of 50mm and a mold closing height of 200mm; Cooling system: A cooling water circulation system is adopted, and the cooling water temperature is controlled at 20 - 30°C to prevent the workpiece from overheating and deforming; Process flow optimization: Pre-punching: Pre-punch holes in the tearing area, with a hole diameter of 0.5mm and a pitch of 2.0mm; Gradual tearing: A multi-stage tearing process is adopted, with each stage of tearing amount controlled at 0.5 - 1.0mm to gradually complete the final tearing.

[0017] A preferred embodiment of the present invention includes: Step 7, quality inspection: Fracture morphology inspection: Through optical microscope observation, the fracture of the workpiece after tearing should be a smooth 45° inclined plane without obvious burrs; Dimensional accuracy inspection: The dimensional deviation of the workpiece after tearing is controlled within ±0.05mm, the electron microscope shows that the thickness of the grain deformation layer ≤5μm, and the tensile test shows that the tensile strength retention rate is 98.3%.

[0018] Compared with the prior art, the embodiment of the present invention provides a precision medical device stamping and forming system and method based on a controllable tearing process, having the following beneficial effects: (1), The present invention adopts a progressive tearing mold design: By multi-stage tearing, stress concentration is reduced, and the precision and quality of parts are improved. Optimize stamping parameters: Through the reasonable matching of speed, pressure and lubricant, an efficient and low-damage tearing effect is achieved. High-precision control: The dimensional tolerance and surface roughness meet the requirements of precision medical device parts. (2) The present invention improves material utilization rate and reduces costs; It is applicable to a variety of materials and thickness ranges, and has strong process versatility; The performance of the torn products is stable, the surface quality is high, and it meets the high-precision requirements of medical devices. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic structural diagram of a precision medical device stamping and forming system based on a controllable tearing process provided by an embodiment of the present application.

[0021] Figure 2 It is a schematic structural diagram of a sheet metal part before tearing provided by an embodiment of the present application.

[0022] Figure 3 This is the microscopic morphology diagram of the sheet metal part after tearing by the precision medical device stamping and forming system provided in the embodiment of the present application.

[0023] Figure 4 This is the tearing process flow chart of a precision medical device stamping and forming method based on a controllable tearing process provided in the embodiment of the present application. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. The "upper", "lower", "front", "rear", "left", "right", etc. used when describing the installation position or direction of the structure or components in this embodiment are based on the orientation of the given drawings. They are only for the convenience of description to distinguish the relative positions of the components or directions, and do not represent the orientation when the device or components in this embodiment are used.

[0025] As Figure 1 shown, the embodiment of the present invention provides a precision medical device stamping and forming system based on a controllable tearing process, including a lower support plate 1. The lower support plate 1 is connected to a lower die base 3 through a lower pad foot 2. A lower backing plate 4 is arranged on the lower die base 3, and a lower template 5 is arranged on the lower backing plate 4. A stock plate 6 is arranged on the lower template 5. The stock plate 6, the lower template 5 and the lower backing plate 4 are connected to the lower die base 3 through two first lifting guide pins 7. A lower limit post 12, a lower die cutting edge 8, a forming insert 9, a stripper block 10 and an inner limit post 11 are arranged inside the lower template 5. The lower die base 3 is connected to an upper die base 14 through an outer guide post 13. The upper die base 14 is sequentially connected to an upper backing plate 15, an upper clamping plate 16, a stop plate 17 and a stripper plate 18 through an inner guide post 21. The circular holes aligned with the upper clamping plate 16, the stop plate 17 and the stripper plate 18 are connected with a forming punch 21 and a punching punch 22. Hooks 19 are connected to the sides of the upper backing plate 15, the upper clamping plate 16, the stop plate 17 and the stripper plate 18.

[0026] A lower limit post 12 is further arranged at the end of the lower die base 3, and an upper limit post 20 is further arranged at the end of the upper die base 14. The upper die base 14 is also connected to the upper backing plate 15 and the upper clamping plate 16 through a second lifting guide pin 24. The upper die base 14 is prepared by using a polycrystalline diamond coating, and its surface roughness Ra ≤ 0.05 μm. The lower die base 3 is a multi-stage buffer structure with a silica gel layer + disc spring group, and its elastic modulus gradient distribution is 0.5 - 5 GPa. The punching punch 22 adopts a conical or stepped punch to reduce stress concentration.

[0027] Refer toFigure 4 The embodiment of the present invention further provides a precision medical device stamping and forming system and method based on a controllable tearing process, which is implemented by a precision medical device stamping and forming system based on a controllable tearing process of the above embodiment, and includes the following steps:

[0028] Step 1, weakening structure design: a) pre-set micron-scale grooves along the target contour line, with a depth of 30-50μm and a width of 50-80μm; b) use picosecond laser processing, and the heat-affected zone is less than 5μm; c) groove angle control: tilted at 75°±2° to the plate plane along the optimized tearing direction.

[0029] Step 2, dynamic load control: a) Initial stage: 500-800N preload is maintained for 0.5-1.0s to eliminate material rebound; b) Tearing stage: step loading, peak pressure 2000±50N, loading rate 50N / ms; c) Real-time feedback from pressure sensor, accuracy ±1.5%, using HBMU9C sensor measured data.

[0030] Step 3, composite mold structure: a) The gap between the upper and lower molds is controlled at 0.01-0.03 mm to ensure tearing accuracy; Stamping parameter optimization: a) The punch speed is controlled at 50-100 mm / s to avoid deformation of the workpiece due to excessive impact; According to the thickness of the sheet metal and the material strength, the stamping pressure range is adjusted to 10-50 MPa; The tearing force is optimized through finite element simulation, and the tearing force is controlled at 1.2-1.5 times the yield strength of the material; The pre-loading technology is used to reduce the rebound of the sheet metal after tearing, and the rebound is controlled within 0.02 mm.

[0031] A precision medical device stamping method based on a controllable tearing process also includes: Step 4, lubrication and cooling: Lubricant: Use a water-based lubricant with a concentration of 2% to 5% to reduce friction and mold wear. Cooling system: Use circulating cooling water, and control the temperature at 20 to 30°C to avoid overheating of the material and resulting in performance degradation. Tearing process: Multi-stage tearing: The separation of sheet metal parts is gradually completed through multi-stage molds to reduce the stress of a single tear; Precision control: The dimensional tolerance of the sheet metal after tearing is controlled within ±0.02mm, and the surface roughness Ra≤1.6μm.

[0032] A precision medical device stamping method based on a controllable tearing process also includes: step 5, material selection and pretreatment: applicable materials: applicable to 304 stainless steel, 420 stainless steel, low carbon steel, the material thickness range is 0.2 to 2 mm; surface pretreatment: the workpiece surface needs to be sandblasted, the roughness Ra ≤ 1.6 μm, to increase the bite force during tearing.

[0033] A precision medical device stamping and forming method based on a controllable tearing process further includes: Step 6, mold design: The surface of the mold cavity needs to be hardened, and the surface roughness is controlled at Ra0.4 - 0.8μm; A tearing groove is pre-designed on the sheet metal part, with a groove width of 0.5mm and a depth of 1 / 2 of the sheet metal thickness; Equipment and process parameters: Press parameters: A hydraulic press is selected, with a punch stroke of 50mm and a mold closing height of 200mm; Cooling system: A cooling water circulation system is adopted, and the cooling water temperature is controlled at 20 - 30°C to prevent the workpiece from overheating and deforming; Process flow optimization: Pre-punching: Pre-punch holes in the tearing area, with a hole diameter of 0.5mm and a pitch of 2.0mm; Gradual tearing: A multi-stage tearing process is adopted, with the tearing amount per stage controlled at 0.5 - 1.0mm to gradually complete the final tearing.

[0034] A precision medical device stamping and forming method based on a controllable tearing process further includes: Step 7, quality inspection: Fracture morphology inspection: Through optical microscopy observation, the fracture surface of the workpiece after tearing should be a smooth 45° inclined plane without obvious burrs; Dimensional accuracy inspection: The dimensional deviation of the workpiece after tearing is controlled within ±0.05mm, the electron microscope shows that the thickness of the grain deformation layer ≤ 5μm (traditional process ≥ 15μm), and the tensile test shows that the tensile strength retention rate is 98.3% (traditional process 91.2%).

[0035] Experimental data verification, as shown in Table 1:

[0036] Table 1 Comparative tests on φ5mm circular stamped parts processed from 0.25mm thick Ti6Al4V plates

[0037] Index Traditional stamping Process of the present invention Test standard Dimensional tolerance (mm) ±0.08 ±0.03 ISO 2768 Section roughness (μm) Ra3.2 Ra1.6 ISO 4287 Processing efficiency (pieces / min) 120 180 - Mold life (ten thousand times) 15-20 50+ ISO 12103 Material saving rate - 27% Mass balance method

[0038] Example 1

[0039] Material: 304 stainless steel, thickness 0.5mm.

[0040] Process parameters: Stamping speed 2m / s, punching force 200kN, lubricant concentration 3%.

[0041] Result: The dimensional tolerance of the sheet metal part after tearing is ±0.015mm, and there are no obvious burrs on the surface, meeting the requirements of precision parts for medical devices. Refer to Figure 2 and Figure 3 , such as the tearing small elastic piece 25.

[0042] Example 2

[0043] Material: 420 stainless steel, thickness 1.2mm.

[0044] Process parameters: Stamping speed 1.5m / s, punching force 300kN, lubricant concentration 4%.

[0045] Result: After tearing, the surface roughness Ra of the sheet metal part is 0.6 μm, without cracks, and has excellent performance. Refer to Figure 2 and Figure 3 。

[0046] Although the present invention has been disclosed above with preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those of ordinary skill in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A precision medical device stamping and forming system based on a controllable tearing process, characterized in that, It includes a lower supporting plate (1), the lower supporting plate (1) is connected to a lower die base (3) through lower feet (2), a lower backing plate (4) is arranged on the lower die base (3), a lower template (5) is arranged on the lower backing plate (4), a blanking plate (6) is arranged on the lower template (5), and the blanking plate (6), the lower template (5) and the lower backing plate (4) are connected to the lower die base (3) through two first lifting guide pins (7). A lower limit post (12), a lower die cutting edge (8), a forming insert block (9), a stripper block (10) and an inner limit post (11) are arranged in the lower template (5); the lower die base (3) is connected to an upper die base (14) through an outer guide post (13), and the upper die base (14) is sequentially connected to an upper backing plate (15), an upper clamping plate (16), a stop plate (17) and a stripper plate (18) through an inner guide post (21); round holes where the upper clamping plate (16), the stop plate (17) and the stripper plate (18) are aligned are connected with a forming punch (21) and a punching punch (22), and hooks (19) are connected to the sides of the upper backing plate (15), the upper clamping plate (16), the stop plate (17) and the stripper plate (18).

2. The precision medical device stamping and forming system based on a controllable tearing process according to claim 1, characterized in that, A lower limit post (12) is further arranged at the end of the lower die base (3).

3. A precision medical device stamping and forming system based on a controllable tearing process according to claim 2, characterized in that, An upper limit post (20) is further arranged at the end of the upper die base (14), and the upper die base (14) is further connected to the upper backing plate (15) and the upper clamping plate (16) through a second lifting guide pin (24).

4. A precision medical device stamping and forming system based on a controllable tearing process according to claim 3, characterized in that, The upper die base (14) is prepared by using a polycrystalline diamond coating, and its surface roughness Ra≤0.05μm; the lower die base (3) is a multi-stage buffer structure with a silica gel layer and a disc spring group, and its elastic modulus gradient distribution is 0.5-5GPa.

5. A precision medical device stamping and forming system based on a controllable tearing process according to claim 4, characterized in that, The punching punch (22) adopts a conical or stepped punch to reduce stress concentration.

6. A precision medical device stamping and forming method based on a controllable tearing process, which is realized by using a precision medical device stamping and forming system based on a controllable tearing process as described in claim 5, characterized in that, It includes the following steps: Step 1, weakening structure design: a) Preset micron-level grooves along the target contour line, with a depth of 30-50μm and a width of 50-80μm; b) Use picosecond laser processing, and the heat affected zone <5μm; c) Groove angle control: Incline at 75°±2° along the optimized tearing direction and the plane of the sheet. Step 2, dynamic load control: a) Initial stage: Keep a pre-tightening force of 500-800N for 0.5-1.0s to eliminate material springback; b) Tearing stage: Step-by-step loading, with a peak pressure of 2000±50N and a loading rate of 50N / ms; c) The pressure sensor gives real-time feedback with an accuracy of ±1.5%, and the actual measured data is obtained by using an HBMU9C type sensor. Step 3, composite die structure: a) Control the gap between the blanking plate and the stripper plate to be 0.01-0.03mm to ensure tearing accuracy. Stamping parameter optimization: a) The punch speed is controlled at 50 - 100 mm / s to avoid workpiece deformation caused by excessive impact; according to the thickness and material strength of the sheet metal, the stamping pressure range is adjusted to 10 - 50 MPa; the tearing force is optimized through finite element simulation, and the tearing force is controlled at 1.2 - 1.5 times the yield strength of the material; the preloading technology is adopted to reduce the springback of the sheet metal after tearing, and the springback is controlled within 0.02 mm.

7. A precision medical device stamping and forming method based on a controllable tearing process according to claim 6, characterized in that, Including: Step 4, Lubrication and Cooling: Lubricant: Use water-based lubricant with a concentration of 2% - 5% to reduce friction and die wear. Cooling system: Adopt circulating cooling water with the temperature controlled at 20 - 30 °C to avoid performance degradation caused by material overheating; Tearing process: Multi-stage tearing: The separation of the sheet metal is gradually completed through multi-stage dies to reduce the stress of single tearing; Precision control: The dimensional tolerance of the sheet metal after tearing is controlled within ±0.02 mm, and the surface roughness Ra ≤ 1.6 μm.

8. A precision medical device stamping and forming method based on a controllable tearing process according to claim 7, characterized in that, Including: Step 5, Material Selection and Pretreatment: Applicable materials: Suitable for 304 stainless steel, 420 stainless steel, and low-carbon steel, with the material thickness range of 0.2 - 2 mm; Surface pretreatment: The surface of the workpiece needs to be sandblasted with a roughness Ra ≤ 1.6 μm to improve the bite force during tearing.

9. A precision medical device stamping and forming method based on a controllable tearing process according to claim 8, characterized in that, Including: Step 6, Die Design: The cavity surface of the die needs to be hardened, and the surface roughness is controlled at Ra0.4 - 0.8 μm; Tearing grooves are pre-designed on the sheet metal, with a groove width of 0.5 mm and a depth of 1 / 2 of the sheet metal thickness; Equipment and process parameters: Punch press parameters: Select a hydraulic punch press with a punch stroke of 50 mm and a die closing height of 200 mm; Cooling system: Adopt a cooling water circulation system with the cooling water temperature controlled at 20 - 30 °C to prevent workpiece overheating and deformation; Process flow optimization: Pre-punching: Pre-punch holes in the tearing area with a hole diameter of 0.5 mm and a pitch of 2.0 mm; Gradual tearing: Adopt a multi-stage tearing process, with each stage of tearing amount controlled at 0.5 - 1.0 mm to gradually complete the final tearing.

10. A precision medical device stamping and forming method based on a controllable tearing process according to claim 9, characterized in that, Including: Step 7, Quality Inspection: Fracture morphology inspection: Through optical microscopy observation, the fracture of the workpiece after tearing should be a smooth 45° inclined plane without obvious burrs; Dimensional accuracy inspection: The dimensional deviation of the workpiece after tearing is controlled within ±0.05 mm, the electron microscope shows that the thickness of the grain deformation layer ≤ 5 μm, and the tensile test shows that the tensile strength retention rate is 98.3%.

Images