A manufacturing equipment and method of a precise wheel core for winding a lithium battery separator

Abstract

The application discloses a kind of lithium battery separator winding precision wheel core manufacturing equipment and manufacturing method, the die of manufacturing equipment includes fixed mould, movable mould and core, fixed mould includes one cylindrical hole-shaped mold cavity opened on fixed mould plate, movable film includes the upper movable mould plate and lower movable mould plate stacked together, the middle part of the upper movable mould plate is equipped with first core, the middle part of the lower movable mould plate is equipped with second core, the second core is located inside the first core, the bottom surface of the mold cavity of the fixed mould plate and the top surface of the second core form the gate of the mold cavity;Fixed mould plate is provided with fixed film cooling waterway in mold cavity wall, first core is provided with first movable mould cooling waterway inside, second core is provided with second movable mould cooling waterway inside, so that wheel core injection molding part can be quickly cooled, reduce the forming shrinkage of wheel core injection molding part, to realize through a small amount of machining can reach the high quality requirement of wheel core.

Description

TECHNICAL FIELD

[0001] The present application relates to plastic parts forming manufacturing technology, in particular to a kind of lithium battery separator winding precision wheel core manufacturing equipment and manufacturing method. BACKGROUND

[0002] Lithium battery separator is one of the key inner components of lithium battery, mainly to separate the positive and negative of battery, its performance determines the interface structure, internal resistance of battery, etc., directly affects the capacity, cycle and safety performance and service life of battery, lithium battery separator is generally made of high-strength thin polyolefin porous membrane, in addition to thickness, surface density, mechanical properties these basic requirements, the size and distribution uniformity of separator micropore also have high requirements.

[0003] The area of lithium battery separator is proportional to the storage capacity of lithium battery. To increase the area of battery separator, the only way is to reduce the thickness of lithium battery separator for the battery of certain volume. Lithium battery separator is expensive, and the thinner the separator, the higher the price. Most of the existing lithium battery separators are 0.012mm thick, and thinner ones can be made to 0.004mm. Because lithium battery separator is very thin and has high performance requirements, even a little dust, burr or bump can pierce the battery separator and cause short circuit, which may even lead to fire and explosion. Therefore, the wheel core used for winding lithium battery separator also needs to have high quality requirements, and must be a precision wheel core with uniform density, low surface roughness, high cylindricity and coaxiality, appropriate hardness and toughness, otherwise it will affect the product quality of the lithium battery separator wound thereon.

[0004] The precision winding wheel for lithium battery separator is referred to as precision winding wheel hereinafter,

[0005] The basic structure of the precision winding wheel in the prior art is shown in Figure 1 , which includes an outer ring 100, an inner ring 200 and a radial connecting rib 300 connecting the outer ring 100 and the inner ring 200. The outer ring 100 is used to wind the separator, the inner ring 200 is used as a clamping reference, and the connecting rib 300 ensures that the precision wheel core has sufficient mechanical strength.

[0006] The traditional precision winding wheel is usually made by injection molding, and the injection mold is shown in Figure 2 , which generally consists of a fixed mold a and a movable mold b mounted on an injection molding machine, a pouring system c located on the fixed mold a, a push-out mechanism d located on the movable mold b for demolding, a guide component e for ensuring that the fixed mold a and the movable mold b can be accurately centered when the mold is closed, and a cooling and heating system, etc. The fixed mold a includes a concave mold of the fixed mold plate, and the movable mold b includes a convex mold of the movable mold plate. The concave mold and the convex mold are combined to form the cavity of the injection molded part. For complex injection molded parts, a core is also needed to cooperate with the concave mold and the convex mold to form the cavity of the injection molded part.

[0007] During the injection molding process, molten plastic is first injected into the mold cavity. After filling, the melt cools and solidifies to form the part. When the part is removed from the mold, it shrinks, a process known as molding shrinkage. Due to this shrinkage characteristic of plastics, the internal stress generated by the connecting ribs 300 during the cooling process of the precision take-up wheel can pull on the outer ring 100 and inner ring 200, causing the outer ring 100 and inner ring 200 to sag and deform at the locations connected to the connecting ribs.

[0008] To ensure the cylindricity, coaxiality, and surface quality requirements of the outer and inner rings of a precision winding wheel, according to existing injection molding principles, the effects of molding shrinkage can generally be reduced by designing the connecting rib 300 to be only half the thickness of the outer and inner rings. However, due to the mechanical strength requirements of a precision winding wheel, the connecting rib thickness must be at least 0.9 times the thickness of the outer and inner rings to meet these strength requirements. Therefore, the connecting rib thickness of a precision winding wheel must exceed the thickness specified by existing injection molding technology to reduce molding shrinkage, resulting in significant molding shrinkage. Furthermore, the thicker the connecting rib, the more severe the impact on the wheel core quality.

[0009] Therefore, the existing injection molding process cannot directly produce a precision winding wheel that meets the mechanical strength, coaxiality, surface cylindricity and surface roughness required for lithium battery diaphragm winding. The outer and inner ring surfaces of the precision winding wheel must be further machined after injection molding.

[0010] In summary, the existing production method of precision winding wheels is to reserve a certain amount of machining allowance on the inner and outer surfaces of the precision winding wheels during injection molding, and then perform turning or grinding after injection molding to meet its design requirements. Its shortcomings are:

[0011] ⑴ The deeper the depth of the inner and outer ring surface allowances removed by machining after injection molding, the higher the probability of scrap rate.

[0012] Because the outer ring 100 and the inner ring 200 of the precision winding wheel have relatively thick walls, the precision winding wheel obtained by injection molding using the existing technology generally has a shrinkage depression depth of about 2 mm at the connecting ribs on the outer and inner cylindrical surfaces. That is, the depth of the surface excess removed by machining must reach 2 mm.

[0013] However, the outer ring 100 and inner ring 200 of the precision winding wheel may contain injection molding pinholes and shrinkage holes. After turning or grinding to remove the machining allowance, these pinholes and shrinkage holes may be exposed. The greater the surface thickness removed by machining, the greater the possibility of pinholes and shrinkage holes. Once the precision winding wheel is machined and the injection molding pinholes and shrinkage holes are exposed, it becomes scrap.

[0014] ⑵Surface machining is prone to burn the surface of the precision winding wheel:

[0015] Since the surface finish requirements of the precision winding wheel are particularly high, when high-speed turning or polishing is carried out by mechanical processing equipment, it is easy for the surface to be burned due to the local heat resistance of the plastic, resulting in waste.

[0016] In summary, the existing technology has the above-mentioned conflicting processing requirements for the subsequent machining of the precision winding wheel for lithium battery diaphragm injection molding, which is difficult to balance, resulting in a high scrap rate in the production of lithium battery diaphragm winding wheel cores, resulting in relatively high manufacturing difficulty and cost. Summary of the Invention

[0017] One of the purposes of the present invention is to provide a precision wheel core manufacturing equipment for lithium battery diaphragm winding, which can reduce the pinholes and shrinkage holes of precision winding wheel injection molded parts, thereby reducing the amount of machining after injection molding, not only improving the processing quality of the winding wheel core, but also greatly improving its production yield.

[0018] The first invention object of the present invention is achieved through the following technical measures: A precision wheel core manufacturing equipment for lithium battery diaphragm winding, comprising a mold, the mold comprising a fixed mold, a movable mold and a core, characterized in that the fixed mold comprises a cylindrical hole-shaped mold cavity opened on the fixed mold plate, the movable mold comprises an upper movable mold plate and a lower movable mold plate stacked together, a first core is installed in the middle of the upper movable mold plate, a second core is installed in the middle of the lower movable mold plate, the second core is located inside the first core, and the first core, the second core and the mold cavity of the fixed mold plate constitute a wheel core mold cavity, the mold cavity comprises an outer ring hole, an inner ring hole and radial rib holes, the outer ring hole and the inner ring hole are connected through the rib holes, wherein the outer ring hole is formed between the mold cavity of the fixed mold plate and the outer wall of the first core, the inner ring hole is formed between the inner wall of the first core and the outer wall of the second core, the rib holes are evenly distributed on the first core, and the bottom surface of the mold cavity of the fixed mold plate and the top surface of the second core form the runner of the mold cavity;

[0019] A fixed film cooling water channel is provided in the mold cavity wall of the fixed mold plate, a first movable mold cooling water channel is provided inside the first core, and a second movable mold cooling water channel is provided inside the second core. The fixed film cooling water channel is a rectangular wave-shaped cooling water channel surrounding the outside of the outer ring hole and connected by a horizontal water channel and a vertical water channel. One vertical water channel is provided on each side of the extension direction of each rib hole to the outside of the wheel core; the first movable mold cooling water channel includes a plurality of interconnected first core vertical water channels arranged between adjacent rib holes; the second movable mold cooling water channel includes a plurality of second core vertical water channels annularly distributed on the inner side of the inner ring hole and connected, and each second core vertical water channel is correspondingly arranged in the length direction of the rib hole.

[0020] The manufacturing equipment of the application is used for manufacturing a precision wheel core with high requirements of mechanical strength, coaxiality, surface cylindricity and surface roughness, the mold and the core can be made of high-thermal-conductivity steel material, the fast cooling of the wheel core is realized through the fixed mold cooling water path, the first movable mold cooling water path and the second movable mold cooling water path, the size accuracy and stability of the wheel core are ensured, especially the cooling water path is as close as possible to the connecting rib of the wheel core, the connecting rib is locally rapidly cooled, the forming shrinkage of the connecting rib is further reduced, the influence of the forming shrinkage of the connecting rib on the outer ring and the inner ring is reduced, then a high-quality precision wheel core is obtained through a small amount of machining, and the problem that the injection molding part of the wheel core and the machining are difficult to balance due to the conflicting machining requirements in the prior art is solved.

[0021] The application also has the following preferred design:

[0022] The first movable mold cooling water path and the second movable mold cooling water path of the application are connected to ice water near the freezing point to rapidly cool the connecting ribs of the wheel core.

[0023] The gate of the application includes a main runner and a sub-runner corresponding to each rib hole, so that the molten plastic uniformly flows to each rib hole through the sub-runner, ensuring the uniformity of the injection molded product.

[0024] The fixed mold of the application has a fixed mold insert, a sprue bushing is installed on the fixed mold insert, and a fixed mold insert cooling water path is further arranged in the fixed mold insert to control the forming shrinkage of the wheel core injection molded part.

[0025] The manufacturing equipment of the application further includes a water gap cutting device for cutting the water gap on the wheel core injection molded part.

[0026] The manufacturing equipment of the application further includes a surface machining device, which includes a wheel core clamp, a turning mechanism and a chip extraction mechanism. The machining of plastic products is different from that of metal. Metal processing is not easy to deform, the surface can be cooled with water or cooling oil, and can be polished again, while plastic is easy to deform. When selecting a clamp, a large clamping force will deform the wheel core, a small clamping force will cause the wheel core to shake during high-speed rotation, and the wheel core will become a waste product after machining. The wheel core clamp of the application is an internal expansion clamp, which clamps the wheel core by expanding the inner hole of the wheel core, increases the contact area between the clamp and the inner hole of the wheel core as much as possible, and meets the requirement of clamping the wheel core without deforming the wheel core.

[0027] The turning mechanism is used to turn and remove the outer ring surface of the wheel core, and to remove the rough surface left by the wheel core at the cut-out nozzle position. The turning of plastic products is also different from that of metals. In metal turning, since the metal surface is hard and heat-resistant, iron chips wrapped around the metal surface have little effect. However, when turning the wheel core, once plastic wire is wrapped around the surface, since the plastic is not heat-resistant, the friction between the plastic wire and the wheel core surface will cause the wheel core to be scrapped. Therefore, the chip extraction mechanism of the present invention uses negative pressure to suck away the chips, i.e., plastic wire, generated during the turning process. The sucked-away plastic wire can be collected and recycled.

[0028] In order to improve machining efficiency, the turning speed needs to be increased. However, the higher the turning speed, the greater the heat generated, which is easy to burn plastic parts. Therefore, a cooling air duct is provided on the tool holder on which the turning tool of the turning mechanism is installed. The outlet of the cooling air duct is arranged directly opposite the bottom of the turning tool. The compressed air flow flows from the bottom of the turning tool to the tool tip to cool the turning tool.

[0029] In order to ensure the surface roughness of the outer ring of the wheel core after turning, the turning tool of the turning mechanism adopts a quick-change machine-clamped blade that does not need to be reground. The tip radius of the turning tool is 0.8mm. The turning tool can use an alloy blade for turning aluminum. Scientifically select the blade and combine it with compressed air to cool the turning tool tip to achieve the purpose of high-speed turning of plastic parts.

[0030] A second object of the present invention is to provide a method for manufacturing a precision wheel core for winding lithium battery separators, comprising the following steps:

[0031] A wheel core injection molded part is obtained by high-pressure injection molding of a mold, a sprue of the wheel core injection molded part is cut off, an outer ring surface of the wheel core injection molded part is first turned, and then a rough surface left at the sprue position is turned off to obtain a precision wheel core;

[0032] During the injection molding process, ice water near the freezing point is introduced into the first and second cores of the dynamic membrane of the mold to quickly cool the connecting ribs of the wheel core and reduce the shrinkage of the connecting ribs. Before turning, the inner hole of the wheel core injection molded part is inflated by an internal expansion fixture. During the turning process, the chips are removed in time, and the turning tool and cutting point are cooled by compressed air flow.

[0033] The mold of the present invention adopts four-stage injection for high-pressure injection molding, wherein the injection pressure of the first stage is 2.5 MPa and the injection speed is 30%; the injection pressure of the second stage is 13.5 MPa and the injection speed is 95%; the injection pressure of the third stage is 14 MPa and the injection speed is 55%; the injection pressure of the fourth stage is 13 MPa and the injection speed is 45%, wherein the injection pressure and injection speed are obtained according to experiments to reduce shrinkage deformation of the injection molded parts.

[0034] The present invention has the following significant effects:

[0035] 1. The fixed mold, the first core and the second core of the injection mold of the present invention are all provided with cooling water channels, so that the outer ring, the inner ring and the connecting ribs of the wheel core can be cooled quickly, reducing the possible shrinkage holes of pinholes in the wheel core injection molded parts, and the cooling water channels are as close as possible to the connecting ribs of the wheel core, so that the thicker connecting ribs can be locally cooled quickly, further reducing the molding shrinkage of the connecting ribs, and reducing the influence of the molding shrinkage of the connecting ribs on the outer ring and the inner ring. The vertical water channel of the second core is arranged in the length direction of the rib hole, which can especially reduce the influence of the shrinkage of the connecting ribs on the inner ring, so that the surface of the inner ring can meet the quality requirements without machining, thereby ensuring the dimensional accuracy and stability of the wheel core injection molded parts.

[0036] 2. The wheel core injection molding of the present invention uses an internal expansion clamp during machining to maximize the contact area between the clamp and the inner hole of the wheel core, thereby achieving the purpose of clamping the wheel core without deformation during turning.

[0037] 3. When the wheel core of the present invention is turned, the chips, i.e., plastic filaments, generated during the turning process are sucked away by negative pressure, thereby preventing the chips from contacting the wheel core and causing the wheel core to be scrapped. At the same time, the chips can be collected and recycled.

[0038] 4. In order to increase the turning speed of the wheel core, the present invention uses compressed air to cool the tip and cutting point of the turning tool to avoid high temperature burning of the wheel core surface, thereby improving processing efficiency and ensuring product quality.

[0039] In summary, through the precision wheel core manufacturing equipment of the present invention, the molding shrinkage of the wheel core injection molded parts is reduced through a special mold, and then a precision wheel core with high quality requirements can be produced through a small amount of machining, so that the wheel core density is uniform, with lower surface roughness, higher cylindricity and coaxiality, thereby improving the yield rate, increasing work efficiency, and reducing product manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Figure 1 A three-dimensional diagram of a precision wheel core for winding lithium battery separators that can be manufactured by the present invention;

[0042] Figure 2 This is the structural principle diagram of the existing injection mold;

[0043] Figure 3 This is an appearance diagram of the wheel core injection mold of the present invention;

[0044] Figure 4 is a partial cross-sectional view of the wheel core injection mold of the present invention;

[0045] Figure 5 for Figure 4 A-A sectional view in the middle;

[0046] Figure 6 for Figure 4 Middle B-B cross-sectional view;

[0047] Figure 7 This is a three-dimensional diagram of the fixed mold of the wheel core injection mold of the present invention;

[0048] Figure 8 A three-dimensional diagram of the movable mold of the wheel core injection mold of the present invention, which includes the wheel core injection molded part;

[0049] Figure 9 For the present invention Figure 8 A three-dimensional image of the middle moving mold after removing the wheel core injection molding;

[0050] Figure 10 This is a top view of the positional relationship between the wheel core and the cooling water channel of the present invention. This figure is a design rendering. In application, the fixed mold cooling water channel is set inside the fixed mold cavity wall, in application, the first movable mold cooling water channel is set inside the first core, and in application, the second movable mold cooling water channel is set inside the second core;

[0051] Figure 11 This is a three-dimensional diagram of the positional relationship between the wheel core and the cooling water channel of the present invention, which is a design rendering;

[0052] Figure 12 This is a three-dimensional diagram showing the positional relationship between the wheel core and the cooling water channel of the present invention from another angle, which is a design rendering;

[0053] Figure 13 is a three-dimensional diagram of the first core of the present invention, which includes a first movable mold cooling water channel;

[0054] Figure 14 is a cross-sectional view of the first core of the present invention, wherein the arrow indicates the direction of cooling water flow;

[0055] Figure 15 is a three-dimensional diagram of the second core of the present invention, which includes a second movable mold cooling water channel;

[0056] Figure 16 is a cross-sectional view of the second core of the present invention;

[0057] Figure 17 It is a cross-sectional view of the wheel core internal expansion fixture of the present invention;

[0058] Figure 18 for Figure 17 A three-dimensional view of the expansion sleeve of the inner-middle expansion fixture;

[0059] Figure 19 for Figure 17 A three-dimensional view of the tapered locking block of the inward expansion clamp;

[0060] Figure 20 This is a working principle diagram of the turning mechanism and chip extraction mechanism of the present invention.

[0061] Reference numerals

[0062] Wheel core 14: 100, outer ring, 200, inner ring, 300, connecting rib;

[0063] Existing mold: a, fixed mold, b, movable mold, c, pouring system, d, ejection mechanism, e, guide components;

[0064] Embodiment: 1. Fixed mold plate, 1a. Fixed mold cooling water channel, 1b. Horizontal water channel, 1c. Vertical water channel, 2. Upper movable mold plate, 3. Lower movable mold plate, 4. First core, 4a. First movable mold cooling water channel, 4b. First core vertical water channel, 4c. Rib hole, 5. Second core, 5a. Second movable mold cooling water channel, 5b. Second core vertical water channel, 5c. Diverter, 6. Fixed mold insert, 7. Gate sleeve, 8. Opening and closing mold assembly, 9. Panel, 10. Bottom plate, 11. Upper movable mold insert, 12. Ejector plate, 13. Ejector, 14. Wheel core, 15. Fixture, 15a. Expansion sleeve, 15b. Tapered locking block, 16. First tool holder, 16a. Cooling air channel, 17. First turning tool, 18. Horn suction port, 19. Second tool holder. DETAILED DESCRIPTION

[0065] The present invention provides a precision wheel core manufacturing equipment for winding lithium battery diaphragm, comprising: Figures 3 to 16 The mold shown in FIG. 1 includes a fixed mold, a movable mold, and a core. Figures 5 to 9 The fixed mold includes a cylindrical hole-shaped mold cavity opened on the fixed mold plate 1, and the movable mold includes an upper movable mold plate 2 and a lower movable mold plate 3 stacked together. The middle of the upper movable mold plate 2 is installed with a first core 4, and the middle of the lower movable mold plate 3 is installed with a second core 5. The second core 5 is located inside the first core 4. The first core 4, the second core 5 and the mold cavity of the fixed mold plate 1 form a mold cavity of the wheel core 14. The mold cavity includes an outer ring hole, an inner ring hole and radial rib holes 4c. The outer ring hole and the inner ring hole are connected to each other. The annular holes are connected through rib holes 4c, wherein the outer annular holes are formed between the mold cavity of the fixed mold plate 1 and the outer wall of the first core 4, and the inner annular holes are formed between the inner wall of the first core 4 and the outer wall of the second core 5. In the embodiment, there are 8 rib holes 4c, which are evenly distributed on the first core 4. The bottom surface of the mold cavity of the fixed mold plate 1 and the top surface of the second core 5 form the runner of the mold cavity, wherein the outer annular holes correspond to the outer ring of the wheel core 14, the inner annular holes correspond to the inner ring of the wheel core 14, and the rib holes 4c correspond to the connecting ribs of the wheel core 14;

[0066] Combine Figures 10 to 16A fixed mold cooling water channel 1a is provided in the mold cavity wall of the fixed mold plate 1, a first movable mold cooling water channel 4a is provided inside the first core 4, and a second movable mold cooling water channel 5a is provided inside the second core 5. The fixed mold cooling water channel 1a is a rectangular wave-shaped cooling water channel surrounding the outside of the outer ring hole and connected by a horizontal water channel 1b and a vertical water channel 1c. A vertical water channel 1c is provided on both sides of each rib hole 4c in the extension direction to the outside of the wheel core 14; the first movable mold cooling water channel 4a includes each first core vertical water channel 1c connected between adjacent rib holes 4c. Road 4b; the second movable mold cooling water channel 5a includes a plurality of second core vertical water channels 5b which are annularly distributed on the inner side of the inner ring hole and are connected to each other. Each second core vertical water channel 5b is correspondingly arranged in the length direction of the rib hole 4c. The above cooling water channels can realize rapid cooling of the outer ring and the inner ring of the wheel core 14, and the vertical water channel 1c, the first core vertical water channel 4b, and the second core vertical water channel 5b are arranged in parallel close to the connecting ribs of the wheel core 14, so that the connecting ribs of the wheel core 14 are cooled faster, reducing the influence of the forming shrinkage of the connecting ribs on the outer ring and the inner ring.

[0067] As a preferred embodiment:

[0068] In order to reduce the impact of molding shrinkage on the dimensional accuracy and stability of the injection molded parts, the first movable mold cooling water channel 4a and the second movable mold cooling water channel 5a are both connected to a chiller, and ice water near the freezing point is introduced to quickly cool the connecting ribs of the wheel core 14.

[0069] The runner of this embodiment includes a main runner and branch runners 5c corresponding to each rib hole 4c one by one, so that the molten plastic flows evenly to each rib hole through the branch runners 5c, thereby ensuring the uniformity of the injection molded product.

[0070] In this embodiment, the fixed mold plate 1 is connected to the panel 9, and the fixed mold plate 1 has a fixed mold insert 6. A gate sleeve 7 is installed on the fixed mold insert 6. The gate sleeve 7 is connected to the glue inlet channel of the panel 9, and a fixed mold insert cooling water channel is also provided inside the fixed mold insert 6.

[0071] The manufacturing equipment of the present invention also includes a nozzle cutting device for cutting the nozzle on the wheel core injection molded part. The nozzle cutting device is a prior art. Its working principle and specific structure can be found in the "A Plastic Wheel Injection Molding Nozzle Cutting Device" with announcement number CN208946598U.

[0072] The manufacturing equipment of the present invention also includes a surface machining device, which includes a wheel core clamp, a turning mechanism and a chip extraction mechanism. The machining of plastic products is different from that of metals. Metal processing is not easy to deform, and the surface can be cooled with water or cooling oil, and can also be polished, while plastic is easy to deform. When selecting a clamp, if the clamping force is large, the wheel core 14 will be deformed, and if the clamping force is small, the wheel core 14 will shake during high-speed rotation, and the wheel core 14 will become scrap after turning. The wheel core clamp of this embodiment is an internal expansion type clamp, such as Figures 17 to 19 As shown, the wheel core is clamped by expanding the inner hole of the wheel core 14. The clamp 15 includes an expanding sleeve 15a and a conical locking block 15b arranged inside the expanding sleeve 15a. The conical locking block 15b is pressed into the expanding sleeve 15a to expand the expanding sleeve. The expanding sleeve 15a divides a cylindrical ring into 8 equal parts. By increasing the contact area between the clamp and the inner hole of the wheel core, the requirement of being able to clamp the wheel core without causing deformation of the wheel core is achieved, and turning can be performed.

[0073] The turning mechanism is used to turn and remove the outer ring surface of the wheel core 14, and to remove the rough surface left by the wheel core 14 at the cut-out nozzle position. The turning of plastic products is also different from that of metal. In metal turning, since the metal surface is hard and heat-resistant, iron chips wrapped around the metal surface have little effect. However, when turning the wheel core, once plastic wire is wrapped around the surface, since the plastic is not heat-resistant, the friction between the plastic wire and the wheel core surface will cause the wheel core to be scrapped. In this embodiment, a chip extraction mechanism is provided to suck away the chips, i.e., plastic wire, generated during the turning process through negative pressure. The sucked-away plastic wire can be collected and recycled.

[0074] In order to improve machining efficiency, the turning speed needs to be increased. However, the higher the turning speed, the greater the heat generated, which is easy to burn the plastic parts. The turning tool of the turning mechanism of this embodiment is installed on the tool holder with a cooling air channel. The outlet of the cooling air channel is set directly at the bottom of the turning tool. The compressed air flow flows from the bottom of the turning tool to the tool tip to cool the turning tool. Figure 20 As shown, the first tool holder 16 is hollow to form a cooling air channel 16a, and compressed air is blown to the first turning tool 17 through the outlet of the cooling air channel 16a to cool the first turning tool 17 and achieve the purpose of high-speed turning. The first turning tool 17 is used to turn the outer ring surface of the wheel core 14. In addition, a trumpet suction port 18 and a second tool holder 19 are provided on the tool holder. The trumpet suction port 18 is used to suck away the chips cut by the turning tool, which belongs to the chip extraction mechanism. Its working principle and specific structure can be found in the "A Chip Processing Device for Turning Plastic Parts" with the announcement number CN208945735U. The second tool holder 19 is used to fix the second turning tool (not shown in the figure), and the second turning tool turns the wheel core 14 to remove the rough surface left at the water outlet position.

[0075] In order to ensure the surface roughness of the outer ring of the wheel core after turning, the turning tool of the turning mechanism adopts a quick-change machine-clamped blade that does not need to be reground. The tip radius of the turning tool is 0.8mm, and the turning tool can use an alloy blade for turning aluminum.

[0076] A method for manufacturing a precision wheel core for winding lithium battery separators comprises the following steps:

[0077] A wheel core injection molded part is obtained by high-pressure injection molding of a mold, a sprue of the wheel core injection molded part is cut off, an outer ring surface of the wheel core injection molded part is first turned, and then a rough surface left at the sprue position is turned off to obtain a precision wheel core;

[0078] During the injection molding process, ice water near the freezing point is introduced into the first and second cores of the dynamic membrane of the mold to quickly cool the connecting ribs of the wheel core and reduce the shrinkage of the connecting ribs. Before turning, the inner hole of the wheel core injection molded part is inflated by an internal expansion fixture. During the turning process, the chips are removed in time, and the turning tool and cutting point are cooled by compressed air flow.

[0079] In this embodiment, the mold uses four-stage injection for high-pressure injection molding, with the injection pressure of the first stage being 2.5 MPa and the injection speed being 30%; the injection pressure of the second stage being 13.5 MPa and the injection speed being 95%; the injection pressure of the third stage being 14 MPa and the injection speed being 55%; and the injection pressure of the fourth stage being 13 MPa and the injection speed being 45%, wherein the injection pressure and injection speed are obtained based on experiments to reduce shrinkage and deformation of the injection molded parts.

[0080] In order to ensure the cylindricity of the wheel core surface after molding, the mold cavity adopts a 0.5 degree demoulding slope.

[0081] To ensure reliable demoulding of the wheel core, an ejector plate 12 is provided on the bottom plate 10 of the rear mold. The ejector plate 12 is connected to the upper movable mold plate insert 11 through the ejector pin 13. During the demoulding process, the opening and closing mold assembly 8 is opened, and the mold is pre-ejected by the fixed mold. Then the ejector plate 12, ejector pin 13 and the upper movable mold plate insert 11 are activated to eject the wheel core injection molded part.

[0082] The above embodiments of the present invention do not limit the scope of protection of the present invention, and the embodiments of the present invention are not limited thereto. All other modifications, replacements, or changes made to the above structure of the present invention based on the above contents of the present invention, in accordance with common technical knowledge and customary means in the field, without departing from the above basic technical concept of the present invention, should fall within the scope of protection of the present invention.

Claims

1. A precision wheel core manufacturing equipment for lithium battery diaphragm winding, comprising a mold, wherein the mold comprises a fixed mold, a movable mold and a core, characterized in that: The fixed mold comprises a cylindrical hole-shaped mold cavity opened on the fixed mold plate (1); the movable mold comprises an upper movable mold plate (2) and a lower movable mold plate (3) stacked together; a first core (4) is installed in the middle of the upper movable mold plate (2); a second core (5) is installed in the middle of the lower movable mold plate (3); the second core (5) is located inside the first core (4); the first core (4), the second core (5) and the mold cavity of the fixed mold plate (1) form a wheel core mold cavity; the mold cavity comprises an outer ring hole , an inner annular hole and radial rib holes (4c), the outer annular hole and the inner annular hole are communicated with each other through the rib holes (4c), wherein the outer annular hole is formed between the mold cavity of the fixed mold plate (1) and the outer wall of the first core (4), and the inner annular hole is formed between the inner wall of the first core (4) and the outer wall of the second core (5), the rib holes (4c) are evenly distributed on the first core (4), and the bottom surface of the mold cavity of the fixed mold plate (1) and the top surface of the second core (5) form a runner of the mold cavity; A fixed mold cooling water channel (1a) is provided in the mold cavity wall of the fixed mold plate (1), a first movable mold cooling water channel (4a) is provided inside the first core (4), and a second movable mold cooling water channel (5a) is provided inside the second core (5). The fixed mold cooling water channel (1a) is a rectangular wave-shaped cooling water channel surrounding the outside of the outer ring hole and connected by a horizontal water channel (1b) and a vertical water channel (1c). One vertical water channel (1c) is provided on each side of each rib hole (4c) in the extension direction toward the outside of the wheel core; the first movable mold cooling water channel (4a) includes a plurality of interconnected first core vertical water channels (4b) provided between adjacent rib holes; the second movable mold cooling water channel (5a) includes a plurality of interconnected second core vertical water channels (5b) annularly distributed inside the inner ring hole, and each second core vertical water channel (5b) is provided correspondingly in the length direction of the rib hole (4c); The manufacturing equipment also includes a nozzle cutting device; The manufacturing equipment also includes a surface machining device, which includes a wheel core clamp, a turning mechanism and a chip extraction mechanism. The wheel core clamp is an internal expansion type clamp (15), which achieves the clamping of the wheel core by expanding the inner hole of the wheel core. The turning mechanism is used to remove the outer ring surface of the wheel core by turning, and to remove the rough surface left at the water outlet position of the wheel core. The chip extraction mechanism absorbs the chips generated during the turning process by negative pressure. A cooling air channel is provided on the tool holder on which the turning tool of the turning mechanism is installed. The outlet of the cooling air channel is arranged opposite to the bottom of the turning tool, and the turning tool is cooled by compressed air. The turning tool of the turning mechanism adopts a quick-change machine clamp that does not require re-grinding. The tip radius of the turning tool is 0.8mm.

2. The precision wheel core manufacturing equipment for lithium battery separator winding according to claim 1, characterized in that: Ice water near the freezing point is introduced into the first movable mold cooling water channel (4a) and the second movable mold cooling water channel (5a) to quickly cool the connecting ribs of the wheel core.

3. The precision wheel core manufacturing equipment for lithium battery separator winding according to claim 2, characterized in that: The runner includes a main runner and a branch runner (5c) corresponding one-to-one to each of the rib holes (4c).

4. The precision wheel core manufacturing equipment for lithium battery separator winding according to claim 3, characterized in that: The fixed mold has a fixed mold insert (6), a sprue sleeve (7) is installed on the fixed mold insert (6), and a fixed mold insert cooling water channel is also provided inside the fixed mold insert (6).

5. A method for manufacturing equipment for manufacturing a precision wheel core for winding lithium battery separators using the equipment according to any one of claims 1 to 4, characterized in that: The following steps are involved: A wheel core injection molded part is obtained by high-pressure injection molding of a mold, a sprue of the wheel core injection molded part is cut off, an outer ring surface of the wheel core injection molded part is first turned, and then a rough surface left at the sprue position is turned off to obtain a precision wheel core; During the injection molding process, ice water near the freezing point is introduced into the first and second cores of the movable mold of the mold to quickly cool the connecting ribs of the wheel core and reduce the shrinkage of the connecting ribs. Before turning, the inner hole of the wheel core injection molded part is propped up by an internal expansion fixture. During the turning process, the chips are removed and the turning tool and cutting point are cooled by compressed air flow.

6. The manufacturing method according to claim 5, characterized in that The mold adopts four-stage injection for high-pressure injection molding, with the injection pressure of the first stage being 2.5 MPa, the injection pressure of the second stage being 13.5 MPa, the injection pressure of the third stage being 14 MPa, and the injection pressure of the fourth stage being 13 MPa.

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