A compaction device and method for a precast soft-hard hybrid composite material

Abstract

This invention discloses a compaction device and method for a soft-hard hybrid woven composite preform, belonging to the technical field of carbon fiber preform molding process. It includes a pressure detection device, a preform compaction fixture, and a preform loading mechanism. The pressure detection device is installed and fixed, and connected to an upper pressure orifice plate. When the upper pressure orifice plate reaches a preset pressure threshold, the controller, based on a dynamic pressure signal, directs the preform to a second position. Then, the controller receives a displacement signal generated by a photoelectric sensor and controls the lower pressure orifice plate to move to a third position. The preform undergoes repeated weaving and compaction to obtain the formed fabric. This invention achieves dynamic control of interlayer pressure in the soft-hard hybrid woven three-dimensional fabric, ensuring consistent interlayer density and improving the preform molding quality.

Description

Technical Field

[0001] This invention belongs to the technical field of carbon fiber preform molding process, and in particular relates to a compaction device and method for a soft-hard hybrid composite preform. Background Technology

[0002] Due to its excellent properties such as low density, high strength and low ablation rate, soft and hard hybrid composite materials have been widely used as the preferred material for the throat liner of solid rocket engines.

[0003] The soft and hard hybrid preform serves as the fiber-reinforced structural skeleton of the composite material. It adopts a molding method of fiber pultrusion carbon rods and carbon fiber bundles. The carbon rods are arranged in an equidistant triangle with close spacing perpendicular to the horizontal plane, and the fibers are laid in triaxial layers between the carbon rods. It has good isotropy, ablation resistance and designability.

[0004] During the forming process of precast components, the degree of densification in the thickness direction determines its internal structure. Manual compaction can easily damage the fiber bundles. Furthermore, the interlayer spacing of the precast components is inconsistent after each compaction and densification process, making it impossible to accurately control the fiber volume content. As a result, the interlayer density of the formed precast components varies greatly, and the forming quality is inconsistent.

[0005] Therefore, there is an urgent need to invent a compaction device and method for prefabricated soft and hard hybrid composite materials, which is mainly used to achieve online dynamic control of the interlayer density of the prefabricated material, improve the molding efficiency and quality of the prefabricated material, and ensure the consistency of mass-produced products. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a compaction device and method for a preform of a soft-hard hybrid woven composite material, which is used in the whole machine weaving process of soft-hard hybrid three-dimensional fabrics to assist in the online control of the interlayer density of the preform, accurately control the volume content of the preform fiber, ensure the consistency of the interlayer density of the preform, and improve the molding efficiency and quality of the preform.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a compaction device for a soft-hard hybrid composite precast body, comprising a pressure detection device, a precast body compaction fixture, and a precast body loading mechanism. The pressure detection device is connected to the precast body compaction fixture and is used to detect dynamic pressure signals and transmit them to a controller. The controller compares the current loading value with a preset pressure threshold to ensure variable pressure loading between precast body layers. The precast body compaction fixture is installed on the precast body loading mechanism. The precast body compaction fixture includes an upper pressure plate, a precast body skeleton, and a lower pressure plate, serving as the object for precast body weaving and compaction.

[0008] Furthermore, the pressure detection device is installed symmetrically on both sides of the top of the frame, transmitting dynamic compaction signals to the controller to ensure that the precast body is uniformly loaded on the horizontal plane. The pressure detection device includes a sensor support, a sensor support plate, a pressure sensor, and a contact block. The upper surface of the sensor support plate is connected to the sensor support, and the sensor support plate has a groove suitable for the size of the pressure sensor. The upper surface of the pressure sensor is connected to the sensor support, and the lower surface of the pressure sensor is connected to the upper surface of the contact block for easy installation and positioning. The sensor support plate is fixedly connected to the frame.

[0009] Furthermore, the preform skeleton includes carbon rods and carbon fiber bundles, and the upper and lower pressure plates are provided with the same equidistant micropores for the uniform arrangement and insertion of carbon rods.

[0010] Furthermore, the upper pressure orifice plate includes an orifice plate fixing ring, an orifice plate, and linear bearings. The orifice plate fixing ring is connected to the orifice plate, and linear bearings are evenly distributed around the circumference of the orifice plate.

[0011] Furthermore, the precast loading mechanism is installed at the bottom of the frame. The precast loading mechanism includes a first lifting plate, a guide column, a first support plate, a lead screw, a second lifting plate, and a second support plate. The first support plate and the second support plate are fixedly connected by the column. The second support plate serves as the base plate of the frame and is threadedly connected to the foundation. The first lifting plate and the second lifting plate are fixedly connected by the guide column. The second lifting plate is fixed to the nut of the lead screw to complete the loading of force and torque. The lead screw is driven to rotate by the drive device, thereby driving the precast body to be fed and compacted.

[0012] This invention also provides a method for compacting a precast soft-hard hybrid composite material, comprising the following steps:

[0013] S1. Initially, the pressure plate is in the first position (weaving in place). After the preform is woven for one cycle, the driving device drives the pressure plate to compact the preform.

[0014] S2. During the pressing process, the upper pressure plate is used to bear the load and transmit the load force to the pressure detection device. The pressure detection device is used to detect whether the preform loading reaches the preset pressure threshold and control the preform to form uniformly.

[0015] S3. The pressure detection device transmits the dynamic pressure signal to the controller, which compares the current loading value with the preset pressure threshold to ensure variable pressure loading between precast layers.

[0016] If the current load value is less than the preset pressure threshold, the controller outputs a pulse signal to drive the drive device to continue loading;

[0017] If the current load value reaches the preset pressure threshold, the specified prefab will move to the second position;

[0018] S4. After the preform reaches the second position, the controller receives the displacement signal and controls the pressure plate to move to the third position, ready to weave into the next cycle.

[0019] Furthermore, in step S3, the preset pressure threshold is determined and calculated by the interlayer pressure formula. When the number of compaction cycles is less than the number of fatigue cycles, the preset pressure threshold increases with the increase of the number of braided layers and the number of compaction cycles. When the number of compaction cycles is greater than or equal to the number of fatigue cycles, the preset pressure threshold is a fixed pressure loading value.

[0020] Furthermore, in step S3, the calculation process for the preset pressure threshold is as follows:

[0021] When the number of compaction cycles is less than the number of fatigue compaction cycles, the compaction load changes linearly with the number of compaction cycles. Based on Hooke's Law, the following formula is derived, and the preset pressure threshold is calculated according to the following formula:

[0022]

[0023] in, , F represents the preset pressure threshold of the precast body; t represents the number of times the precast body is compacted; n represents the number of interlacing points in the cross-section of precast bodies of different sizes; G represents the material shear modulus; D represents assuming the interlacing point is the mean diameter of the spring; d represents assuming the interlacing point is the wire diameter of the spring. This represents the deformation of each cycle of the prefab; This indicates the amount of springback in each cycle of the preform;

[0024] When the number of compaction cycles is greater than or equal to the number of fatigue cycles, the compaction load does not change with the number of compaction cycles and is calculated according to the following formula, which represents the pressure threshold that needs to be set after different sized precast bodies reach the fatigue point:

[0025]

[0026] in, This indicates the number of fatigue test points during precast compaction.

[0027] Furthermore, in step S4, the third position is the position reached after adding the compaction thickness of each precast body to the first position; the compaction thickness of each precast body is determined and calculated using the interlayer displacement formula.

[0028] If the number of compaction cycles is less than the number of fatigue compaction cycles, the following formula shall be used for calculation:

[0029]

[0030] If the number of compaction cycles is greater than or equal to the number of fatigue cycles, the distance increase each time is a fixed value, calculated using the following formula:

[0031] .

[0032] Furthermore, in step S4, the displacement signal is emitted by a photoelectric sensor, which is installed at the first position, the upper limit position of the prefabricated body weaving, and the lower limit position.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention assists an automatic weaving machine for soft and hard hybrid prefabricated structures in producing three-dimensional fabrics. A pressure detection device monitors in real time whether the prefabricated loading value reaches a preset pressure threshold. Different preset pressure thresholds are selected based on different weaving thicknesses to ensure vertical layer consistency within the prefabricated structure. A photoelectric sensor controls the lifting height to maintain a uniform height across the weaving area, enabling online control of the interlayer density of the soft and hard hybrid three-dimensional fabric. This precisely controls the fiber volume content of the prefabricated structure, improving the efficiency and quality of prefabricated structure forming. Attached Figure Description

[0035] The present invention will be described in detail below with reference to the accompanying drawings and examples. The advantages and implementation methods of the present invention will become more apparent from this description. The accompanying drawings are for illustrative purposes only and do not constitute any limitation on the present invention. In the accompanying drawings:

[0036] Figure 1 This is a schematic diagram of the preform compaction device of the present invention.

[0037] Figure 2 This is a schematic diagram of the pressure detection device of the present invention.

[0038] Figure 3 This is a schematic diagram of the structure of the pressure plate of the present invention.

[0039] Figure 4 This is the control principle diagram of the present invention.

[0040] Figure 5 This is a schematic diagram of the preform compaction process of the present invention.

[0041] Figure 6 This is a schematic diagram of the weaving and interlacing points of the preform of the present invention.

[0042] Figure 7 This is a schematic diagram of the compaction principle of the preform in this invention, where the number of compaction cycles is less than the number of fatigue compaction cycles.

[0043] Figure 8 This is a schematic diagram of the compaction principle of the preform of the present invention, in which the number of compaction cycles is greater than or equal to the number of fatigue compaction cycles.

[0044] In the picture:

[0045] 1. Frame; 2. Pressure detection device; 3. Precast compaction fixture; 4. Precast loading mechanism; 201. Sensor support; 202. Sensor support plate; 203. Pressure sensor; 204. Contact block; 31. Upper pressure orifice plate; 32. Carbon rod; 33. Carbon fiber bundle; 34. Lower pressure orifice plate; 301. Orifice plate fixing ring; 302. Orifice plate; 303. Linear bearing; 401. First lifting plate; 402. Guide column; 403. First support plate; 404. Lead screw; 405. Second lifting plate; 406. Synchronous pulley; 407. Servo motor; 408. Second support plate. Detailed Implementation

[0046] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0047] like Figures 1 to 8 As shown, the present invention discloses a precast compaction device for a soft-hard hybrid composite material, comprising a pressure detection device 2, a precast compaction fixture 3, and a precast loading mechanism 4. The pressure detection device 2 is installed on both sides of the top of the frame 1 and is connected to the precast compaction fixture 3. It is used to detect dynamic pressure signals and transmit them to the controller. The controller compares the current loading value with a preset pressure threshold to ensure variable pressure loading between precast layers. The precast loading mechanism 4 is installed at the bottom of the frame 1, and the precast compaction fixture 3 is installed on the precast loading mechanism 4.

[0048] The pressure detection device 2 includes a sensor support 201, a sensor support plate 202, a pressure sensor 203, and a contact block 204. The upper surface of the sensor support plate 202 is threadedly connected to the sensor support 201. The sensor support plate 202 has a groove suitable for the size of the pressure sensor 203, and positioning grooves are milled on both the upper and lower surfaces that contact the pressure sensor 203 to ensure verticality of installation. The upper surface of the pressure sensor 203 is threadedly connected to the sensor support 201, and the lower surface of the pressure sensor 203 is threadedly connected to the upper surface of the contact block 204 for easy installation and positioning. The upper surface of the contact block 204 has a groove milled to fit the pressure sensor 203. The sensor support plate 202 is fixed to the frame 1 by a threaded connection.

[0049] Among them, the pressure detection device 2 is installed symmetrically on the left and right (divided into the first pressure sensor and the second pressure sensor), which transmits the dynamic compaction signal to the controller to ensure that the precast body is uniformly loaded on the horizontal plane.

[0050] The preform compaction fixture 3 includes an upper pressure plate 31, a preform skeleton, and a lower pressure plate 34. As the object of preform weaving and compaction, the preform skeleton includes carbon rods 32 and carbon fiber bundles 33. The upper pressure plate 31 and the lower pressure plate 34 are provided with the same equidistant microholes for the uniform arrangement and insertion of carbon rods 32. The carbon rods 32 are arranged in a regular hexagonal shape, and the carbon fiber bundles 33 are woven in a cyclic manner in the 0°, 120°, and 240° directions in their narrow slit channels.

[0051] The upper pressure orifice plate 31 includes an orifice plate fixing ring 301, an orifice plate 302, and linear bearings 303. The orifice plate fixing ring 301 and the orifice plate 302 are connected by threads, and six linear bearings 303 are evenly distributed around the circumference of the orifice plate 302.

[0052] The precast loading mechanism 4 includes a first lifting plate 401, guide columns 402, a first support plate 403, a lead screw 404, a second lifting plate 405, a second support plate 408, a synchronous pulley 406, and a servo motor 407. The first support plate 403 and the second support plate 408 are fixedly connected by four columns. The second support plate 408 serves as the base plate of the frame 1 and is threaded to the foundation. The first lifting plate 401 and the second lifting plate 405 are fixedly connected by four guide columns 402. The second lifting plate 405 is fixed to the lead screw 404 with a nut to complete the loading of force and torque. The servo motor 407 drives the synchronous pulley 406 to rotate through the synchronous belt. The synchronous pulley 406 is interference-fitted with the lead screw 404, which drives the lead screw 404 to rotate, thereby driving the precast body to be fed and compacted.

[0053] The precast compaction fixture 3 and the first lifting plate 401 are positioned by pins and connected by threads.

[0054] This invention also provides a method for compacting a precast soft-hard hybrid composite material, comprising the following steps:

[0055] S1. Initially, the pressure plate 34 is in the first position (weaving original position). After the preform is woven for one cycle, the servo motor 407 drives the lead screw 404 to drive the pressure plate 34 to compact the preform.

[0056] S2, during the pressing process, the upper pressure plate 31 is used to bear the load and transmit the load force to the pressure detection device 2. The pressure sensor 203 of the pressure detection device 2 is used to detect whether the preform loading reaches the preset pressure threshold and control the preform to form uniformly.

[0057] S3, pressure sensor 203 transmits dynamic pressure signal to controller, controller compares current loading value with preset pressure threshold to ensure variable pressure loading between precast layers;

[0058] If the current load value is less than the preset pressure threshold, the controller outputs a pulse signal to drive the servo motor 407 to continue loading;

[0059] If the current load value reaches the preset pressure threshold, the specified prefab will move to the second position;

[0060] As can be seen, determining the second position first requires calculating the corresponding preset pressure threshold, and then comparing it with the current load value returned by the pressure sensor 203. Different braided loop layers need to have their preset pressure thresholds calculated in turn.

[0061] S4. After the preform reaches the second position, the controller receives the displacement signal and controls the pressure plate 34 to move to the third position, ready to weave and enter the next cycle.

[0062] The precast components are repeatedly woven and compacted, and compacted to the corresponding height at different weaving thicknesses to achieve dynamic variable thickness compaction and density of the precast body, ensuring consistent density between layers.

[0063] In step S3, after the preform is woven for one cycle, it is compacted once. A pressure threshold needs to be specified. The preset pressure threshold is determined and calculated by the interlayer pressure formula: when the number of compaction times is less than the number of fatigue times, the preset pressure threshold increases with the increase of the number of weaving layers and the number of compaction times; when the number of compaction times is greater than or equal to the number of fatigue times, the preset pressure threshold is a fixed pressure loading value.

[0064] Further, in step S3, taking any one weaving cycle as an example, the calculation process for the preset pressure threshold is as follows: The compaction law of the soft-hard mixed weaving precast body shows that the pressure threshold of the precast body is related to the weaving thickness of the precast body. There are compaction fatigue points corresponding to different weaving layers in the number of compaction cycles, so it is necessary to preset the pressure threshold. The determination calculation includes:

[0065] like Figure 7 As shown, when the number of compaction cycles is less than the number of fatigue compaction cycles, the compaction load changes linearly with the number of compaction cycles. Based on Hooke's Law, the following formula is derived, and the preset pressure threshold is calculated according to the following formula:

[0066]

[0067] in, , F represents the preset pressure threshold of the precast body; t represents the number of times the precast body is compacted; n represents the number of interlacing points in the cross-section of precast bodies of different sizes; G represents the material shear modulus; D represents assuming the interlacing point is the mean diameter of the spring; d represents assuming the interlacing point is the wire diameter of the spring. This represents the deformation of each cycle of the prefab; This indicates the amount of springback in each cycle of the preform.

[0068] like Figure 8As shown, when the number of compaction cycles is greater than or equal to the number of fatigue cycles, the compaction load does not change with the number of compaction cycles. It is calculated according to the following formula, which represents the pressure threshold that needs to be set after different sized precast bodies reach the fatigue point:

[0069]

[0070] in, This indicates the number of fatigue test points during precast compaction.

[0071] Figure 7 and Figure 8 In this context, 'u' represents the original weave height of a single layer of the prefabricated body.

[0072] Among them, such as Figure 6 As shown, the number of interlacing points n needs to be calculated based on the size of the woven preform. The mean diameter D of the spring and the wire diameter d change with the spacing of the carbon rods 32. The number of preform compaction fatigue cycles is determined by compaction experiments under different weaving sizes.

[0073] In step S4, the third position is the position reached after adding the compaction thickness of each precast body to the first position; the compaction thickness of each precast body is calculated using the interlayer displacement formula to ensure that the weaving position remains unchanged.

[0074] like Figure 7 As shown, if the number of compaction cycles is less than the number of fatigue compaction cycles, the following formula shall be used for calculation:

[0075]

[0076] like Figure 8 As shown, if the number of compaction cycles is greater than or equal to the number of fatigue cycles, the distance increase each time is a fixed value, calculated using the following formula:

[0077]

[0078] In step S4, the displacement signal is emitted by a photoelectric sensor, which is installed at the first position (weaving home position), the upper limit position of the preform weaving, and the lower limit position. The upper and lower limit positions of the preform weaving need to be determined according to the positions of the shaped fabrics with different thicknesses.

[0079] In this embodiment, as Figure 4 As shown, the controller needs to determine the magnitude of the loading force of the pressure sensors 203 on the left and right sides and the displacement signal transmitted by the photoelectric sensor, so as to adopt the corresponding loading control strategy and output pulse signals to the servo driver to drive the servo motor 407 in real time. The controller's display screen can display the data provided by the pressure sensor 203 in real time, so as to improve the visibility and safety of the compaction degree.

[0080] The controller includes, but is not limited to, common electromechanical control devices or equipment such as computers and PLC programmable controllers.

[0081] Furthermore, in this embodiment, the carbon rods 32 of the soft and hard hybrid woven preform are arranged in a regular hexagonal pattern, and the carbon fiber bundles 33 are woven in a loop from three directions of 0°, 120° and 240° respectively. This is a preferred design. The compaction method of this preform is not limited to this. For example, when the carbon rods 32 are arranged in a regular quadrilateral array, or when the carbon fiber bundles 33 are woven in different directions to form a similar preform, only a suitable load-bearing compaction plate needs to be processed to compact and densify it using this example method.

[0082] In summary, this invention can detect in real time whether the loading value of the preform reaches the preset pressure threshold, select different preset pressure thresholds according to different weaving thicknesses, ensure the consistency of the layers in the vertical direction of the preform, and control the lifting and lowering of the preform loading mechanism 4 through photoelectric sensors to always keep the weaving area at a uniform height, realize online control of the interlayer density of soft and hard mixed three-dimensional fabric, accurately control the fiber volume content of the preform, and improve the molding efficiency and quality of the preform.

[0083] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A method for compacting a precast soft-hard hybrid composite material, characterized in that: The compaction method is achieved using a precast compaction device for a soft-hard hybrid composite material. This device includes a pressure detection device, a precast compaction fixture, and a precast loading mechanism. The pressure detection device is connected to the precast compaction fixture, which is mounted on the precast loading mechanism. The precast compaction fixture includes an upper pressure plate, a precast skeleton, and a lower pressure plate. The compaction method includes the following steps: S1. Initially, the pressure plate is in the first position. After the preform is woven into a cycle, the driving device drives the pressure plate to compact the preform. S2. During the pressing process, the upper pressure plate is used to bear the load and transmit the load force to the pressure detection device. The pressure detection device is used to detect whether the preform loading reaches the preset pressure threshold and control the preform to form uniformly. S3. The pressure detection device transmits the dynamic pressure signal to the controller. The controller compares the current loading value with the preset pressure threshold. If the current loading value is less than the preset pressure threshold, the controller outputs a pulse signal to drive the drive device to continue loading. If the current loading value reaches the preset pressure threshold, the preform is designated to reach the second position. S4. After the preform reaches the second position, the controller receives the displacement signal and controls the pressure plate to move to the third position, ready to weave and enter the next cycle. In step S3, the preset pressure threshold is determined and calculated by the interlayer pressure formula. When the number of compaction times is less than the number of fatigue times, the preset pressure threshold increases with the increase of the number of braided layers and the number of compaction times; when the number of compaction times is greater than or equal to the number of fatigue times, the preset pressure threshold is a fixed pressure loading value. In step S3, the calculation process for the preset pressure threshold is as follows: When the number of compaction cycles is less than the number of fatigue compaction cycles, the compaction load changes linearly with the number of compaction cycles. Based on Hooke's Law, the following formula is derived, and the preset pressure threshold is calculated according to the following formula: in, , ; F This indicates the preset pressure threshold of the precast structure; t Indicates the number of times the precast structure was compacted; n This indicates the number of interlacing points in the cross-section of precast structures of different sizes; G Indicates the material's shear modulus; D This indicates that the point of intersection is assumed to be the mean diameter of the spring; d This indicates that the interlacing point is assumed to be the wire diameter of the spring; This represents the deformation of each cycle of the prefab; This indicates the amount of springback in each cycle of the preform; When the number of compaction cycles is greater than or equal to the number of fatigue cycles, the compaction load does not change with the number of compaction cycles and is calculated according to the following formula, which represents the pressure threshold that needs to be set after different sized precast bodies reach the fatigue point: in, Indicates the number of compaction fatigue points of the precast structure; In step S4, the third position is the position reached after adding the compaction thickness of each precast body to the first position; the compaction thickness of each precast body is calculated using the interlayer displacement formula. If the number of compaction cycles is less than the number of fatigue compaction cycles, the following formula shall be used for calculation: If the number of compaction cycles is greater than or equal to the number of fatigue cycles, the distance increase each time is a fixed value, calculated using the following formula: 。 2. The method for compacting a precast soft-hard hybrid composite material according to claim 1, characterized in that: The pressure detection device is installed symmetrically on both sides of the top of the frame. The pressure detection device includes a sensor support, a sensor support plate, a pressure sensor, and a contact block. The upper surface of the sensor support plate is connected to the sensor support. The sensor support plate has a groove suitable for the size of the pressure sensor. The upper surface of the pressure sensor is connected to the sensor support. The lower surface of the pressure sensor is connected to the upper surface of the contact block. The sensor support plate is connected and fixed to the frame.

3. The method for compacting a precast soft-hard hybrid composite material according to claim 1, characterized in that: The preform skeleton includes carbon rods and carbon fiber bundles, and the upper and lower pressure plates are provided with the same equidistant micropores.

4. The method for compacting a precast soft-hard hybrid composite material according to claim 1, characterized in that: The upper pressure orifice plate includes an orifice plate fixing ring, an orifice plate, and linear bearings. The orifice plate fixing ring is connected to the orifice plate, and linear bearings are evenly distributed around the circumference of the orifice plate.

5. The method for compacting a precast soft-hard hybrid composite material according to claim 1, characterized in that: The precast loading mechanism is installed at the bottom of the frame. The precast loading mechanism includes a first lifting plate, a guide column, a first support plate, a lead screw, a second lifting plate, and a second support plate. The first support plate and the second support plate are fixedly connected by the column. The second support plate is threaded to the ground as the frame base plate. The first lifting plate and the second lifting plate are fixedly connected by the guide column. The second lifting plate is fixed to the nut of the lead screw. The lead screw is driven to rotate by a drive device, which drives the precast body to be fed and compacted.

6. The method for compacting a precast soft-hard hybrid composite material according to claim 1, characterized in that: In step S4, the displacement signal is emitted by a photoelectric sensor, which is installed at the first position, the upper limit position of the prefabricated body weaving, and the lower limit position.

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