A 3D printer for chain slings and a method for manufacturing chain slings

Abstract

A chain sling 3D printer and a method for preparing a chain sling, belonging to the technical field of continuous fiber composite material 3D printing. The specific scheme is as follows: A chain sling 3D printer includes a print head, a tray, a reduction gear set and a motor. The motor is connected to the reduction gear set in a cooperative manner. The reduction gear set is connected to the tray through a plurality of electromagnetic clutches. An annular groove is provided on the upper surface of the tray, and a through hole is provided in the middle of the tray. The print head is movably arranged above the tray. The tray includes a first half-ring and a second half-ring, and the first half-ring and the second half-ring are detachably and fixedly connected. The present invention adopts a new continuous fiber 3D printing path in cooperation with the rotation of the tray, which can increase the fiber volume content in the printed and formed part, improve the mechanical properties of the interface bonding, and reduce the porosity.

Description

Technical Field

[0001] The present invention belongs to the technical field of continuous fiber composite material 3D printing, and particularly relates to a chain sling 3D printer and a method for manufacturing a chain sling using the 3D printer. Background Art

[0002] Continuous fiber reinforced composite materials have a series of excellent properties such as high specific strength, high specific modulus, strong weather resistance, and low density, and are widely used in fields such as aerospace and civil industries. Compared with short fiber and long fiber reinforced composite materials, continuous fiber reinforced composite materials have excellent mechanical properties and designability (the elastic modulus of the composite material is the highest when the load is parallel to the fiber, and the lowest when the load is perpendicular to the fiber). Continuous fiber reinforced composite materials are composed of reinforcing fibers, matrix materials, and the interface phase between the two. The reinforcing fibers mainly play a load-bearing role, the matrix materials mainly play a role in connecting the reinforcing phase and transferring the load, and the interface, as another important microstructure of the composite material, not only plays a role as a bridge connecting the reinforcing fibers and the resin matrix, but also serves as a link for the external load to be transferred from the matrix to the reinforcing fibers. The structure, composition, properties, bonding mode, and interfacial bonding strength of the interface have a significant impact on the mechanical properties and failure behavior of the composite material. Therefore, improving the interfacial properties of continuously fiber 3D printed reinforced composite materials is of great significance for the application and development of fiber reinforced composite materials.

[0003] 3D printing technology has a relatively high degree of printing freedom and can manufacture continuous fiber reinforced composite material parts with complex structures. Continuous fiber 3D printing technology is to simultaneously feed continuous fibers and matrix materials into a 3D printing head, extrude continuous fiber composite material filaments for 3D part printing and forming, and the continuous fiber five-axis 3D printer head technology has begun mass production and use. However, it is still a technical blank to print high-strength chain slings using a continuous fiber 3D printer.

[0004] 3D printing technology is an additive manufacturing technology. Different from traditional 3D printing, in the process of 3D printing continuous fiber composite materials, in combination with the mixture rule of composite materials, the mechanical properties of 3D printed continuous fiber composite material parts can be specifically controlled by controlling the printing path and pressure of the continuous fiber composite material.

[0005] A chain sling is composed of multiple chain links that are mutually enclosed, connected end to end, and nested together. Both ends of each chain link are semi-circular, and the middle is connected by two cylinders. They are structural chain links that cooperate with each other but are not connected to each other. The cross-section in the direction perpendicular to the wire diameter is circular. The demand for chain slings with high strength, light self-weight, corrosion resistance, etc. is increasing day by day. The tensile strength of the chain sling determines whether it can be used, and the surface inert performance determines how long it can be used. Continuous fiber-reinforced composites can replace metals to manufacture chain slings in special fields. To ensure the high strength of the chain sling, each chain link can only be wound by one continuous fiber in the circumferential direction, and there are no wrinkles and the spacing between the fibers is equal. Because the adjacent two chain links are intersecting at 90 degrees and are non-interfering, it is difficult to manufacture high-strength chain slings using traditional 3D printing methods and techniques.

[0006] Problems existing in the existing 3D printing technology of continuous fiber-reinforced composites:

[0007] 1. Currently, there is no dedicated 3D printing path planning method for continuous fiber-reinforced composites. The existing printing paths directly adopt the printing paths of pure resin-based materials. Since pure resin-based materials are isotropic, the mechanical properties of the parts are basically independent of the printing path. The printing paths of existing pure resin materials are realized by the bottom-up filling algorithm. The purpose of these algorithms is to fill the printed plane to form the required structure, without considering the main influence of the printed fiber path on the strength of the parts.

[0008] 2. For 3D printers with short fiber bundles, the mechanical properties in the length direction of adding short fiber bundles have indeed been greatly improved. However, since the short fiber bundles are only laid singly along the length direction, the fibers in the forming trajectory are in a loose and irregular distribution state, which affects the bearing performance of the component. Therefore, there is no effective strengthening between the printing paths and the fiber bundles between the printing layers, and the increase in mechanical parameters in the width direction, especially in the interlayer (height direction), is very limited.

[0009] 3. Currently, high-end 3D printers are equipped with synchronous hot pressing rollers to reduce the interlayer voids and improve the adhesion between the resins in 3D printed products. However, this 3D compaction printing does not form synchronous coordinated control with the fiber path and the tray. The tensile and bending properties of the product are not optimized. In the present invention, continuous fibers are compacted in the upper layer of resin, thereby increasing the fiber volume content, enhancing the interlayer bonding force between adjacent printing layers, and reducing the delamination phenomenon after loading.

[0010] 4. The tray of traditional 3D printers is a flat plate. If printing the bottom surface of a non-flat model, support materials need to be printed and secondary processing such as grinding is required after completion, which has an impact on the strength of the printed body.

[0011] 5. If the outer surface of a traditional 3D printed object needs to be strengthened, only a layer of strengthening material can be added to its surface, which often relies on the combination of the coating material and the surface of the printed part. Even in the way of pasting a fiber mesh on the surface, the pasting process requires a large amount of labor to complete, and the bonding quality between the pasted layer and the printed layer is difficult to guarantee. There is a risk of peeling for both the pasted fiber mesh layer and the coated strengthening layer.

[0012] According to the mechanical anisotropy of continuous fibers, the force structure of chain links, and the control of the 3D printing tray, the present invention plans the optimal fiber path, breaks the traditional 3D printing horizontal slicing and layering method, and innovatively adopts a path of equidistant layering along the arc surface of the product. The cross-section forms a concentric circle structure to avoid delamination due to stress. Based on the misaligned printing theory in the invention patent of

A continuous fiber reinforced composite material with high fiber content and its 3D printing method

A filament pressure implementation mechanism for continuous fiber 3D printing

[0013] The five-axis print head and the tray are synchronously linked and coordinated to keep the printing angle close to 90 degrees. The "arc surface equidistant layering printing path" is pioneered, and technological innovation is carried out with the improvement of part strength as the first element. Summary of the Invention

[0014] To solve the problems in the background technology, the present invention provides a 3D printer for chain slings and a method for preparing chain slings.

[0015] To achieve the above object, the present invention adopts the following technical solutions:

[0016] A 3D printer for chain slings includes a print head, a tray, a reduction gear set, and a motor. The motor is connected to the reduction gear set in a cooperative manner. The reduction gear set is connected to the tray through a plurality of electromagnetic clutches. The upper surface of the tray is provided with an annular groove, and a through hole is provided in the middle of the tray. The print head is movably arranged above the tray. The tray includes a first half-ring and a second half-ring, and the first half-ring and the second half-ring are detachably and fixedly connected.

[0017] Further, the 3D printer for chain slings further includes an annular flash. The annular flash is arranged outside the annular groove, and the inner edge of the annular flash is smoothly transitionally connected to the outer edge of the annular groove.

[0018] Further, the reduction gear set includes a first gear, a second gear, and a third gear. The diameters of the first gear, the second gear, and the third gear increase in sequence. The first gear and the second gear are coaxially and fixedly connected. The second gear is meshed with the output gear of the motor. The first gear is meshed with the third gear. The plurality of electromagnetic clutches are fixedly arranged on the upper surface of the third gear.

[0019] Further, the number of the electromagnetic clutches is four, and they are evenly distributed on the upper surface of the third gear.

[0020] Further, an in-situ photoelectric sensor is arranged on the rotating shaft of the second gear. A first baffle is fixedly arranged on the lower surface of the second gear. The first baffle is arranged in a matching manner with the in-situ photoelectric sensor. The in-situ photoelectric sensor and the motor are both electrically connected to the upper computer controller.

[0021] Further, a clutch photoelectric sensor is arranged on the rotating shaft of the third gear. A plurality of second baffles are arranged on the lower surface of the third gear corresponding to the positions of the plurality of electromagnetic clutches. The width of each second baffle is equal to the width of the corresponding electromagnetic clutch. The clutch photoelectric sensor and the plurality of electromagnetic clutches are both electrically connected to the upper computer controller.

[0022] A method for manufacturing a chain sling by using a chain sling 3D printer includes the following steps:

[0023] Step 1: Start the print head. Starting from any point A at the edge of the side wall of the annular groove a, output continuous fiber composite materials along the annular contour line of point A in the annular groove until reaching the starting point A, and complete the printing of the first circle of the lower half ring.

[0024] Step 2: Move the print head to the lower part of the starting point of the (i - 1)-th circle of the lower half ring as the starting point of the i-th circle. The printing process is the same as that of the first circle of the lower half ring, and complete the printing of the i-th circle of the lower half ring. Then, let i = i + 1, and repeat the above process of Step 2 until printing reaches the bottom of the annular groove, and then print upward in sequence until reaching the edge of the side wall of the annular groove b, that is, complete the printing of the first layer of the lower half ring. Wherein, i ≥ 2.

[0025] Step 3: Above the (j - 1)-th layer of the lower half ring, print several circles along the middle gaps between two adjacent circles of continuous fiber composite materials in the (j - 1)-th layer of the lower half ring to cover the inner side wall of the annular groove formed by the (j - 1)-th layer of the lower half ring, and complete the printing of the j-th layer of the lower half ring. Then, let j = j + 1, and repeat the above process of Step 3 until covering the entire annular groove, and complete the printing of the lower half ring of the chain link. Wherein, j ≥ 2.

[0026] Step 4: Based on step 3, start printing the first circle of the upper half of the chain ring along the central axis of the annular groove, that is, complete the first layer printing of the upper half of the chain ring;

[0027] Step 5: Print one circle at the bottom of both sides of the k-1th layer of the upper half ring, and print one circle in the middle gaps of two adjacent circles of continuous fiber composite materials on the upper surface of the k-1th layer of the upper half ring to complete the printing of the kth layer of the upper half ring; then, let k=k+1, repeat the above process of step 5 until it is printed flush with the edge of the lower half ring in the annular groove, that is, the printing of one chain link in the chain rigging is completed, where k≥2.

[0028] Furthermore, in step three, the position of the first circle of continuous fiber composite material in the odd-numbered layer of the lower half ring is on the same horizontal plane as the position of the first circle of continuous fiber composite material in the first layer of the lower half ring.

[0029] Furthermore, before printing the first circle of the lower half ring, at least one layer of continuous fiber composite material is printed inside the annular groove along the arc direction of the cross-section of the annular groove; after printing the upper half ring, at least one layer of continuous fiber composite material is printed on the upper surface of the upper half ring along the arc direction of the cross-section of the upper half ring.

[0030] Furthermore, during the printing process, the annular groove rotates with the tray, and the printing angle of the print head is 90±20°.

[0031] The present invention compares the effect of traditional continuous fiber 3D printer:

[0032] Traditional printing is to print slices in a path parallel to the tray, which is formed by horizontal stacking of multiple fibers, and is very easy to be delaminated and broken after being subjected to tension. The annular paths of the upper and lower semicircles in the present invention are the first to create a method of equidistant layered printing paths on arc surfaces, and finally form a concentric circle structure, which is only formed by a continuous fiber without wrinkles, and the outer layer is designed with multiple layers of radial fiber binding.

[0033] The present invention adopts a new continuous fiber 3D printing path in conjunction with the rotation of the tray, which can increase the fiber volume content in the printed parts, improve the interface bonding mechanical properties, and reduce the porosity. Therefore, the present invention also has a wider range of applications in the manufacture of annular and circular parts. The manufactured lightweight, high-strength, anti-corrosion chain rigging can be used in many fields such as aviation and navigation, mooring platforms, weapons and equipment, and biomedicine. The present invention provides an effective new idea for preparing continuous fiber reinforced resin-based composite materials that take into account both high precision and high strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The overall structure of the present invention is shown in FIG. Figure 1 ;

[0035] Figure 2 is the schematic diagram of the overall structure of the present invention Figure 2 ;

[0036] Figure 3 is the schematic diagram of the reduction gear set structure Figure 1 ;

[0037] Figure 4 is the schematic diagram of the reduction gear set structure Figure 2 ;

[0038] Figure 5 is the schematic diagram of the tray structure Figure 1 ;

[0039] Figure 6 is the schematic diagram of the tray structure Figure 2 ;

[0040] Figure 7 is the schematic cross-sectional view of the printing path of the lower half ring;

[0041] Figure 8 is the schematic cross-sectional view of the printing path of the upper half ring;

[0042] Figure 9 is the schematic diagram of the radial printing path;

[0043] In the figure, 1. printing head, 2. tray, 3. reduction gear set, 4. motor, 5. electromagnetic clutch, 6. annular groove, 7. through hole, 8. annular flash, 9. in-situ photoelectric sensor, 10. first baffle, 11. clutch photoelectric sensor, 12. second baffle, 21. first half ring, 22. second half ring, 31. first gear, 32. second gear, 33. third gear. Detailed implementation manners

[0044] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0045] In the present invention, the "arc surface" in the "equidistant layer method of arc surface" refers to that each layer of continuous fibers is in an arc surface; "equidistant" means that the distance between every two adjacent circles of continuous fibers on each layer of the arc surface is equal. "Layering" means that the overall printing path has a layered arc surface structure. Detailed implementation manner one

[0047] A 3D printer for chain slings, comprising a print head 1, a tray 2, a reduction gear set 3 and a motor 4. The motor 4 is cooperatively connected with the reduction gear set 3. The reduction gear set 3 is connected to the tray 2 through a plurality of electromagnetic clutches 5. An annular groove 6 is provided on the upper surface of the tray 2, and a through hole 7 is provided in the middle of the tray 2. The print head 1 is movably arranged above the tray 2. The tray 2 includes a first half-ring 21 and a second half-ring 22, and the first half-ring 21 and the second half-ring 22 are detachably and fixedly connected.

[0048] Further, the 3D printer for chain slings further includes an annular flash 8. The annular flash 8 is arranged outside the annular groove 6, and the inner edge of the annular flash 8 is smoothly and transitionally connected with the outer edge of the annular groove 6.

[0049] Further, the reduction gear set 3 includes a first gear 31, a second gear 32 and a third gear 33. The diameters of the first gear 31, the second gear 32 and the third gear 33 increase in sequence. The first gear 31 and the second gear 32 are coaxially and fixedly connected. The second gear 32 is meshed and connected with the output gear of the motor 4. The first gear 31 is meshed and connected with the third gear 33. The plurality of electromagnetic clutches 5 are fixedly arranged on the upper surface of the third gear 33.

[0050] Further, the number of the electromagnetic clutches 5 is four, and they are evenly distributed on the upper surface of the third gear 33.

[0051] Further, an in-situ photoelectric sensor 9 is arranged on the rotating shaft of the second gear 32. A first baffle 10 is fixedly arranged on the lower surface of the second gear 32. The first baffle 10 is matched with the in-situ photoelectric sensor 9. Both the in-situ photoelectric sensor 9 and the motor 4 are electrically connected to the upper computer controller.

[0052] Further, a clutch photoelectric sensor 11 is arranged on the rotating shaft of the third gear 33. A plurality of second baffles 12 are arranged on the lower surface of the third gear 33 corresponding to the positions of the plurality of electromagnetic clutches 5. The width of each second baffle 12 is equal to the width of the corresponding electromagnetic clutch 5. Both the clutch photoelectric sensor 11 and the plurality of electromagnetic clutches 5 are electrically connected to the upper computer controller. Specific Embodiment 2

[0054] A method for preparing a chain sling by using a 3D printer for chain slings, comprising the following steps:

[0055] Step 1: Start the print head 1. Starting from any point A on the edge of the side wall of the annular groove 6a, output continuous fiber composite materials along the annular contour line of point A in the annular groove 6 until reaching the starting point A, and complete the first circle of printing for the lower half-ring.

[0056] Step 2: Move the print head 1 below point A as the starting point of the second circle of the lower half-ring. The printing process is the same as that of the first circle of the lower half-ring to complete the printing of the second circle of the lower half-ring.

[0057] Step 3: And so on. Move the print head 1 below the starting point of the (i - 1)-th circle of the lower half-ring as the starting point of the i-th circle. The printing process is the same as that of the first circle of the lower half-ring to complete the printing of the i-th circle of the lower half-ring. Then, let i = i + 1 and repeat the above process of Step 3 until printing reaches the bottom of the annular groove 6, and then print upward in sequence to the edge of the side wall of the annular groove b, that is, complete the printing of the first layer of the lower half-ring. Wherein, i ≥ 3.

[0058] Step 4: Above the first layer of the lower half-ring, print several circles from the side wall of the annular groove b along the middle gap between two adjacent circles of continuous fiber composite materials in the first layer of the lower half-ring to the side wall of the annular groove a to complete the printing of the second layer of the lower half-ring.

[0059] Step 5: And so on. Above the (j - 1)-th layer of the lower half-ring, print several circles along the middle gap between two adjacent circles of continuous fiber composite materials in the (j - 1)-th layer of the lower half-ring in sequence to cover the inner side wall of the annular groove formed by the (j - 1)-th layer of the lower half-ring to complete the printing of the j-th layer of the lower half-ring. Let j = j + 1 and repeat the above process of Step 5 until covering the entire annular groove 6 to complete the printing of the lower half-ring of the link. Wherein, j ≥ 3. The cross-sectional view of the printing path of the lower half-ring is as Figure 7 shown, and the numbers in the figure indicate the number of printed circles.

[0060] Step 6: On the basis of Step 5, start printing the first circle of the upper half-ring along the central axis of the annular groove, that is, complete the printing of the first layer of the upper half-ring.

[0061] Step 7: Print one circle on both sides of the first circle of the upper half-ring, and print one circle in the middle gap between every two adjacent circles of continuous fiber composite materials to complete the printing of the second layer of the upper half-ring.

[0062] Step 8: Print one circle on both bottom sides of the (k - 1)-th layer of the upper half-ring, and print one circle in the middle gap between two adjacent circles on the upper surface of the (k - 1)-th layer of the upper half-ring to complete the printing of the k-th layer of the upper half-ring. Then, let k = k + 1 and repeat the above process of Step 8 until printing reaches the same level as the edge of the lower half-ring in the annular groove, that is, complete the printing of one link in the chain sling. Wherein, k ≥ 3. The cross-sectional view of the printing path of the upper half-ring is as Figure 8 shown, and the numbers in the figure indicate the number of printed circles.

[0063] Furthermore, in Step 5, the position of the first circle of continuous fiber composite material in the odd-numbered layer of the lower half-ring is on the same horizontal plane as the position of the first circle of continuous fiber composite material in the first layer of the lower half-ring.

[0064] Further, before printing the first circle of the lower half-ring, at least one layer of continuous fiber composite material is printed in a folded-back manner inside the annular groove 6 along the arc direction of the cross-section of the annular groove 6; after printing the upper half-ring, at least one layer of continuous fiber composite material is printed in a folded-back manner on the upper surface of the upper half-ring along the arc direction of the cross-section of the upper half-ring. The radial printing path is as Figure 9 shown.

[0065] Further, during the printing process, the annular groove 6 rotates with the tray 2, and the printing angle of the print head 1 is 90±20°.

[0066] Preferably, when using the chain sling 3D printer described in the first specific embodiment to print the chain link, before printing the first circle of the lower half-ring, at least one layer of continuous fiber composite material is printed in a folded-back manner inside the annular groove 6 along the arc direction of the cross-section of the annular groove 6 from the b side wall of the annular groove 6 to the edge of the annular flash 8 for covering the printed chain link.

[0067] Continuous fiber 3D printing is an automated process that utilizes the true anisotropic properties of continuous fibers by printing continuous paths in the direction of the load conditions. The 3D printing technology does not involve the processes of mold making, layering, molding, and high-temperature and high-pressure curing in composite material forming. It effectively combines the advantages of continuous fiber composite materials and 3D printing to directly achieve end-to-end integrated production.

[0068] I. The technical problems that can be solved by the path planning method in the method for preparing a chain sling using a chain sling 3D printer in the present invention are:

[0069] 1. In the present invention, for the first time, a continuous fiber printing path is used to manufacture a chain link. The lower half-ring and the upper half-ring of the circumferential winding part both adopt a printing path with equally spaced layers on an arc surface, and the cross-section is a concentric circle structure, avoiding the phenomenon of horizontal delamination when stressed, ensuring no wrinkles, no voids between layers, and high tensile strength.

[0070] 2. By scientifically and reasonably planning the path, the problems of slow forming speed and difficult control of performance indicators such as fiber resin volume fraction and fiber resin distribution during the printing and forming process can be overcome, thereby improving the bearing mechanical properties of the component.

[0071] 3. The continuous fiber path is combined with the variable pressure hot pressing roller technology to solve the problems of loose fibers, weak interlayer bonding force, irregular distribution state, and large porosity ratio in the forming trajectory. The new printed layer is offset by half a fiber spacing from the previous printed layer, and the fibers of the new printed layer are laid on the matrix resin bonding part of the previous layer and compacted in a staggered manner.

[0072] 4. The outermost radially wrapped fibers can improve the surface quality of the link, while having good interfacial bonding properties between the fibers and the matrix, high fiber content in the component, and high fiber density. The path planning of the present invention is applicable to fiber tows of any size.

[0073] 5. During the printing process, it can be controlled in real time according to the fiber path, and the proportion of the extruded matrix resin can be adjusted accordingly. Especially in the areas of fiber jumpers and the inner side of the link where it is denser, to prevent the phenomenon of excessive accumulation of the matrix resin in the fiber crossing area.

[0074] II. The technical problems that can be solved by the chain sling 3D printer in the present invention are:

[0075] 1. The surface effect and quality of the component after forming are good, and no secondary processing such as grinding is required. The present invention breaks through the traditional idea of changing the properties of materials.

[0076] 2. It realizes 3D printing with high mechanical properties, high forming efficiency, no corner waste, no support, and the U-shaped cross-section tray is combined with a synchronous variable pressure compaction structure for variable-speed rotation, which can provide an idea for the forming process of continuous ring components with high performance requirements. The variable pressure compaction structure belongs to the prior art and will not be introduced in detail here. The variable-speed rotation is realized by the main control machine.

[0077] 3. The horizontal rotation of the tray and the movement of the print head position can realize the circumferential winding process of a link by one fiber, and the fibers of the upper and lower circles of the cross-section are centrosymmetric, with high mechanical property balance and no possibility of horizontal delamination. The tensile strength of the formed ring is high.

[0078] 4. Since the links in the chain sling are staggered at 90°, during the rotation of the printing target N-ring, it is necessary to avoid the obstruction of the previous link. More than 4 electromagnetic clutches work alternately, which can not only conduct the rotation of the tray, but also make the pin shaft suck into the clutch cavity after being energized at the corresponding position, avoiding hitting the previous link of the target ring.

[0079] Technologies such as printing path planning, tray rotation, variable resin ratio, and radial wrapping in the present invention can solve problems such as low continuous fiber volume content, weak interlayer bonding force, and poor mechanical properties in existing printing methods, improve the continuous fiber volume content, and increase the interlayer bonding force between adjacent printed layers. The control of the variable resin ratio refers to the ability to control in real time according to the fiber path during printing and adjust the ratio of the extruded matrix resin accordingly. Especially in the dense areas inside the fiber jumpers and link rings, to prevent the phenomenon of excessive accumulation of the matrix resin in the fiber crossing area. This technology can also transform the basis of low-cost 3D printing equipment to achieve a machine that can manufacture chain slings with excellent mechanical properties. The "arc equidistant layered path" technology can also be applied to filament winding machines for manufacturing high-strength products such as tension rods, pull rings, power arms, and fiber ropes made of continuous fiber materials.

[0080] Three basic criteria for measuring high-quality continuous fiber composite formed parts are: the volume content of the fiber (i.e., the ratio of the fiber to the matrix material), the porosity, and the straightness of the fiber. Continuous fiber 3D printing forming is different from the whole fiber cloth (fabric or unidirectional) used in traditional continuous fiber dry forming or wet forming. Not only the laying angle of the fiber cloth needs to be considered, but also the single-layer printing contour information and the single-layer stress vector diagram need to be planned according to the placement method of the preform and the printing layer height, and finally a printing program for each layer surface composed of a bundle of fiber paths is obtained.

[0081] Each link circle of the chain sling is a closed ring-shaped mechanical structure unit. According to the material properties of the continuous fiber: it is formed by winding a single fiber circumferentially and then wrapping at least one layer of continuous fiber radially on the outermost layer for the best stress-bearing forming structure. Therefore, the single-layer printing path of this link ring is not the traditional horizontal plane, but is printed by the arc equidistant layering method of the product.

[0082] Example 1

[0083] Define the link ring in the preformed chain sling as the N-ring, the ring connected to the N-ring as N-1, and the next ring connected to the N-ring as N+1. Set the ring diameter D of the N-ring to be 100 mm. The ratios of the inner width and inner length of the load-bearing link ring in the industry to the ring diameter are 1.3D and 3.0D respectively, that is, the inner width of the link ring is 130 mm and the inner length is 300 mm. This size is the most compact structure in the link ring industry.

[0084] This embodiment uses the chain rigging 3D printer described in Specific Implementation Method 1. The tray 2 is in the shape of a disk as a whole, and the material is preferably non-magnetic metal (copper or aluminum). The angle between the plane where the annular flash 8 is located and the upper surface of the tray 2 is 30°±15°. In order to put the N-1 ring into the middle hollow of the tray 2, the tray 2 is divided into two petals along the width direction of the chain ring. The first half ring 21 and the second half ring 22 are combined and locked by the alignment strip and bolts. After the first half ring 21 and the second half ring 22 are combined, the width of the middle hollow is greater than the cross-sectional wire diameter of the N-1 ring, so that the N-1 ring will not be scratched when the tray is rotated horizontally. There are more than four pits on the lower surface of the tray, which are used in contact with the pin of the corresponding electromagnetic clutch to support and rotate the tray.

[0085] N-ring continuous fiber printing path planning:

[0086] According to the mechanical analysis of the finite element simulation model of the N-ring, it is determined that: first, a bundle of continuous fibers completes the circumferential winding of the N-ring, and then multiple layers of radial continuous fibers are wound on the outermost side, which is the best molding process. The width of the continuous fiber bundle is much smaller than the diameter of the cross-section of the N-ring chain ring. The 3D digital model of the circular chain ring is analyzed by computer software, and the continuous fiber bundle is programmed according to the thickness and width to generate a continuous fiber path control CNC program (including: the number of layers of continuous fiber materials, the filling rate of each layer, the printing rate of each layer, the angle between two adjacent layers, and the variable pressure compaction process of each layer of synchronous hot pressing rollers to complete the 3D printing preparation of continuous fiber reinforced composite materials). Transmit telecommunication signals to control the displacement of the five-axis print head and the rotation rate of the coordinated tray rotation motor to complete radial and circumferential printing. It can realize the one-time constant temperature, constant speed, constant pressure, quantitative and fixed printing of each link in the chain rigging, and the cross-section of the formed link part in the wire diameter direction is a regular circle.

[0087] ① Radial fiber path planning: The five-axis continuous fiber printing head outputs continuous fibers along the arc direction of the cross-section of the annular groove 6 from the highest point on the inner side (b side) of the annular groove to the outer edge of the annular flash 8 for printing, completing the printing of the first row of radial fibers. Control the horizontal displacement of the printing head, and start printing the second row of fibers side by side with the first row of radial fibers at a set gap, printing from the outer edge of the annular flash 8 to the inner high point of the annular groove 6. Rotate the tray and adjust the movement of the printing head to make the printing head print and compact the fiber bundle at an angle as close to vertical as possible, and use this path to print row by row tightly until the printed radial fibers meet the starting head of the first row of radial fibers and then stop printing. Under the coordinated control of the five-axis printing head and the tray rotation motor: Complete the printing of the first layer of radial fibers on the annular groove 6 and the annular flash 8 of the tray. When the end fiber of the first layer meets the starting fiber of the first layer, start printing the second layer. The trajectory of each row of the second layer of fibers is above the middle of two adjacent rows of the first layer of fibers, and the printing path is the same as that of the first row. And so on to complete the printing of the second layer of radial fibers. Use this misaligned compaction printing method to print at least 3 layers of radial fibers. Precautions during the printing of radial fibers: (1) The angle between the printing head and the inner surface of the annular groove 6 is controlled within 90°±20°. (2) When printing the arc surface areas on both the inner and outer sides of the chain link, since the areas of the inner and outer arcs are different, the fiber bundles on the inner side are more concentrated, so the resin filling ratio on the inner side is lower than that on the outer side. (3) The distance between each row and each layer of the multi-layer radial fiber bundles is kept consistent, within the range of 0.5-1.5 times the wire diameter of the fiber bundle, and is completed by one continuous fiber bundle. (4) The variable pressure compaction component is installed behind the five-axis printing head, always keeping horizontal with the printing direction of the fibers, and the variable compaction pressure increases with the increase of the fiber layer thickness.

[0088] ② Circumferential fiber path planning:

[0089] (1) The path of the circumferential fiber printing of the lower half-ring of the link is as follows: The five-axis print head starts continuous fiber printing along the circumferential contour line at point A, which is the highest point on the outer side wall of the inner surface of the annular groove 6. The five-axis print head rotates in cooperation with the tray. When printing reaches the starting point A, the first circle of circumferential fiber printing is completed. After the print head moves downward to reach the specified gap from the first circle of fibers, it starts to print the second circle of fibers side by side. And so on, printing down in circles using this path. When the continuous fiber printing reaches the lowest point of the inner surface of the annular groove 6, the print head starts to move upward and starts to print each circle of fibers on the inner side wall of the inner surface of the annular groove 6 until the circumferential fibers wind around to the highest point on the inner side wall of the U-shaped inner surface and then stop printing. At this time, the printing of the first layer of circumferential fibers is completed. After the first layer is completed, the print head presses on the first layer of fibers and starts the second layer of printing. The trajectory of each circle of the second layer of circumferential fibers is above the middle of two adjacent circles of the first layer of fibers, and the path is the same as that of the first layer. Rotate the tray and adjust the movement of the print head, and make circumferential winding from the highest point on the inner side wall of the annular groove 6 to the highest point on the outer side wall of the annular groove 6 in sequence. And so on, complete the printing of the second layer of circumferential fibers, and use this printing method of staggered compaction to print circumferential fibers. Due to the accumulation of the thickness of each layer of fibers, the path of each layer of circumferential fibers gradually decreases, and the print head gradually approaches the center point of the N-ring diameter and finally stops at the center point, making the top of the lower half-ring form a plane, that is, the circumferential fiber printing of the lower half-ring of the wire diameter is completed. (2) The path of the circumferential fiber printing of the upper half-ring of the wire diameter is as follows: The fiber bundle starts to print the first circle in the circumferential direction along the central axis of the circular cross-section from the center point of the N-ring diameter (that is, the stop position of the fiber bundle of the lower half-ring of the wire diameter). After the first circle of fibers winds around to the starting point, the print head moves horizontally inward to start circumferential printing of the second circle. After the second circle of fibers winds around to the starting point, the print head moves horizontally outward to the outside of the first circle to start circumferential printing of the third circle. The first, second, and third circles of fibers are equally spaced and surround in a plane. After the third circle is completed, the print head moves upward to the upper part between the first and third circles of fibers to print the fourth circle of circumferential fibers. After the fourth circle is completed, the print head moves inward to the upper part between the first and second circles of fibers to print the fifth circle of circumferential fibers. The first, second, third, fourth, and fifth circles of fibers form an isosceles trapezoid on the cross-section of the wire diameter. Due to the effect of the synchronous hot pressing roller compaction process, the cross-sections of the first five circles of continuous fibers tend to be semi-circular. Starting from this semi-circle as the second layer, circumferential fiber staggered compaction printing is carried out on the semi-circular arc surface of its cross-section. When each circle of fibers encounters the plane of the lower half-ring of the wire diameter, it starts to print a new layer horizontally and turns back. As the number of printing layers of the circumferential fibers in the upper half-ring increases, the wire diameter of the upper half-ring gradually increases synchronously. When the diameter of the upper half-ring of the wire diameter reaches the set value, stop printing and cut off the continuously wound circumferential fibers, and raise the print head. Precautions during the circumferential fiber printing process: (1) The angle between the print head and the printed surface is controlled within 90°±20° (filling angle).(2) The variable pressure compaction component is installed behind the five-axis print head, always keeping horizontal with the printing direction of the fiber. The variable compaction pressure increases as the thickness of the fiber layer increases.

[0090] (2) In the chain sling 3D printer, the function of the reduction gear set is to horizontally support and rotate the tray steadily. After the 3D printer is powered on and started, the stepping motor drives the tray to rotate at a constant speed through the reduction gear set 3. When the first baffle 10 at the bottom of the tray 2 cuts off the in-situ photoelectric sensor 9, the tray 2 stops rotating and enters the reset standby state. When printing starts, the main control board will output a digital electrical pulse signal to stimulate the stepping motor to rotate. The tray 2 is rotated by the pin shaft of the electromagnetic clutch below. The number of electromagnetic clutches is more than four. Because when printing N rings horizontally, the N - 1 ring is placed vertically and fixed, which will block the support column below the tray during the rotation of the tray. Therefore, the pin shaft of the electromagnetic clutch is used to hold the concave pit below the tray to drive the tray to rotate. When the electromagnetic clutch 5 is about to contact the position of the N - 1 ring during the rotation of the tray, the corresponding second baffle 12 of the electromagnetic clutch 5 will cut off the clutch photoelectric sensor 11 in advance. The clutch photoelectric sensor 11 generates a digital electrical pulse signal, which makes the electromagnetic clutch 5 energize and suck. The pin shaft of the electromagnetic clutch 5 retracts into the interior. The clutch position baffle has a certain width, and the electromagnetic clutch 5 always remains in the sucked state. After the tray 2 rotates a certain angle, that is, after the electromagnetic clutch 5 passes the position of the N - 1 ring, the corresponding clutch position baffle releases the cut-off of the clutch photoelectric sensor 11. After the electromagnetic clutch 5 is powered off, the pin shaft rebounds under the action of the return spring and is stuck into the concave pit below the tray. During the rotation of the tray 2, at least three pin shafts of the electromagnetic clutch 5 are in contact with the tray 2 to ensure the stability of the support. The number of second baffles corresponds to the number of electromagnetic clutches 5 configured on the tray 2. The turntable rotates one week and is initially reset through the first baffle 10. The automatic frequency reference circuit control design starts to record: the first baffle 10 at the first clutch position controls the first electromagnetic clutch 5 to suck, and the subsequent clutch position baffles are sorted to match the electromagnetic clutch 5 in this way.

[0091] (3) Radial wrapping process:

[0092] When the diameter of the upper semi-circle of the wire diameter reaches the set value, stop printing, cut off the continuous fiber of the circumferential winding, and raise the print head. Wrap the printed radial fiber layer back to the upper half-ring of the wire diameter. The radial fiber is in a lap-back wrapping method, and the lap length is more than 10% of the wire diameter, finally forming the N ring of the chain sling. Remove the N ring from the annular groove 6, take away the alignment pressing strip and bolts that imprison the tray, divide the tray into two parts, so that the N - 1 ring can be moved away. Put the tray on the N ring and repeat the above steps to start manufacturing the N + 1 ring until the preparation of the chain sling is completed.

[0093] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a chain sling using a chain sling 3D printer, characterized in that: the chain sling 3D printer includes a print head (1), a tray (2), a reduction gear set (3) and a motor (4), the motor (4) is cooperatively connected with the reduction gear set (3), the reduction gear set (3) is connected to the tray (2) through a plurality of electromagnetic clutches (5), the upper surface of the tray (2) is provided with an annular groove (6), the middle of the tray (2) is provided with a through hole (7), the print head (1) is movably arranged above the tray (2), the tray (2) includes a first half-ring (21) and a second half-ring (22), and the first half-ring (21) and the second half-ring (22) are detachably and fixedly connected; The method for preparing a chain sling using the chain sling 3D printer includes the following steps: Step 1: Start the print head (1), start from any point A on the edge of the side wall of the annular groove (6)a, and output continuous fiber composite materials along the annular contour line of point A in the annular groove (6) until the starting point A is reached, completing the first circle of printing of the lower half-ring; Step 2: Move the print head (1) to the lower part of the starting point of the (i - 1)-th circle of printing of the lower half-ring as the starting point of the i-th circle. The printing process is the same as that of the first circle of printing of the lower half-ring, and the printing of the i-th circle of the lower half-ring is completed; then, let i = i + 1, and repeat the above process of Step 2 until the bottom of the annular groove (6) is printed, and then print upward in sequence until the edge of the side wall of the annular groove b is reached, that is, the printing of the first layer of the lower half-ring is completed; where i ≥ 2; Step 3: Above the (j - 1)-th layer of the lower half-ring, print several circles in sequence along the middle gap between two adjacent circles of continuous fiber composite materials in the (j - 1)-th layer of the lower half-ring to cover the inner side wall of the annular groove formed by the (j - 1)-th layer of the lower half-ring, and complete the printing of the j-th layer of the lower half-ring; then, let j = j + 1, and repeat the above process of Step 3 until the entire annular groove (6) is covered, and the printing of the lower half-ring of the chain link is completed; where j ≥ 2; Step 4: On the basis of Step 3, start printing the first circle of the upper half-ring of the chain link along the central axis of the annular groove, that is, complete the printing of the first layer of the upper half-ring; Step 5: Print one circle on both sides of the bottom of the (k - 1)-th layer of the upper half-ring, and print one circle in the middle gap between two adjacent circles of continuous fiber composite materials on the upper surface of the (k - 1)-th layer of the upper half-ring, and complete the printing of the k-th layer of the upper half-ring; then, let k = k + 1, and repeat the above process of Step 5 until it is printed flush with the edge of the lower half-ring in the annular groove, that is, the printing of one chain link in the chain sling is completed, where k ≥ 2.

2. The method for preparing a chain sling using a chain sling 3D printer according to claim 1, characterized in that: the chain sling 3D printer further includes an annular flash (8), the annular flash (8) is arranged outside the annular groove (6), and the inner edge of the annular flash (8) is smoothly transitionally connected to the outer edge of the annular groove (6).

3. The method for preparing a chain sling using a chain sling 3D printer according to claim 1, characterized in that: The reduction gear set (3) includes a first gear (31), a second gear (32) and a third gear (33). The diameters of the first gear (31), the second gear (32) and the third gear (33) increase in sequence. The first gear (31) and the second gear (32) are coaxially and fixedly connected. The second gear (32) is meshed with the output gear of the motor (4). The first gear (31) is meshed with the third gear (33). The several electromagnetic clutches (5) are fixedly arranged on the upper surface of the third gear (33).

4. A method for manufacturing a chain sling by using a chain sling 3D printer according to claim 3, characterized in that: The number of the electromagnetic clutches (5) is four, and they are evenly distributed on the upper surface of the third gear (33).

5. A method for manufacturing a chain sling by using a chain sling 3D printer according to claim 3, characterized in that: An in-situ photoelectric sensor (9) is arranged on the rotating shaft of the second gear (32). A first baffle (10) is fixedly arranged on the lower surface of the second gear (32). The first baffle (10) is arranged in a matching manner with the in-situ photoelectric sensor (9). The in-situ photoelectric sensor (9) and the motor (4) are both electrically connected to the upper computer controller.

6. A method for manufacturing a chain sling by using a chain sling 3D printer according to claim 5, characterized in that: A clutch photoelectric sensor (11) is arranged on the rotating shaft of the third gear (33). A plurality of second baffles (12) are arranged on the lower surface of the third gear (33) corresponding to the positions of the several electromagnetic clutches (5). The width of each second baffle (12) is equal to the width of the corresponding electromagnetic clutch (5). The clutch photoelectric sensor (11) and the several electromagnetic clutches (5) are both electrically connected to the upper computer controller.

7. A method for manufacturing a chain sling by using a chain sling 3D printer according to claim 1, characterized in that: In the third step, the position of the first circle of continuous fiber composite material in the odd-numbered layers of the lower half ring is on the same horizontal plane as the position of the first circle of continuous fiber composite material in the first layer of the lower half ring.

8. A method for manufacturing a chain sling by using a chain sling 3D printer according to claim 1, characterized in that: Before printing the first circle of the lower half ring, at least one layer of continuous fiber composite material is printed in a folded-back manner along the arc direction of the cross section of the annular groove (6) inside the annular groove (6); after printing the upper half ring, at least one layer of continuous fiber composite material is printed in a folded-back manner along the arc direction of the cross section of the upper half ring on the upper surface of the upper half ring.

9. A method for manufacturing a chain sling by using a chain sling 3D printer according to claim 1, characterized in that: During the printing process, the annular groove (6) rotates with the tray (2), and the printing angle of the print head (1) is 90±20°.

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