A variable diameter die for fiberglass winding

Abstract

The present invention belongs to the technical field of winding molds, and specifically relates to a variable diameter mold for winding fiberglass. It includes a core shaft and an elastic bladder mounted on the outside thereof; wherein the elastic bladder includes plugs at both ends and a plurality of annular fins or spiral fins arranged on the inner surface of the elastic bladder. The annular fins or spiral fins are arranged and mounted on the outside of the core shaft, and their radial directions are inclined and intersected with the axial directions of the core shaft. After the elastic bladder is filled with a medium, the inner edges of the annular fins clamp the core shaft and their outer edges support the elastic bladder to form a variable diameter core mold for winding fiberglass. This new variable diameter mold can adapt to the winding of fiberglass with variable diameter special-shaped components and improve demoulding efficiency through flexible deformation. The composite structure of the bladder material and the core shaft significantly reduces heat conduction and improves the utilization rate of curing heat energy. It has the characteristics of simple and compact structure and easy processing and manufacturing.

Description

Technical Field

[0001] The invention belongs to the technical field of winding molds, and in particular relates to a diameter-variable mold for winding glass fiber reinforced plastics. Background Art

[0002] The FRP winding process is one of the main manufacturing processes for resin-based composite materials. Under the conditions of controlled tension and predetermined linear shape, special winding equipment is used to impregnate continuous glass fiber with resin glue and then continuously, evenly and regularly wind it on a mold or lining. It is then cured under a certain temperature environment and demolded to become a composite material molding method for products of specific shapes.

[0003] Currently, the most commonly used molds in actual production are all metal structures. Their main disadvantages are: first, after winding is completed, when the product is heated and cured, due to the good thermal conductivity of the metal mold, it will absorb and consume a large amount of additional heat energy, increasing the production cost of heating and curing; second, during curing and demolding, due to the shrinkage of the fiberglass product, demolding is difficult and time-consuming. Forceful demolding may even damage the molded product, seriously affecting product quality and causing significant damage to the mold, reducing its service life; third, because metal molds are mostly tubular in shape, they are greatly limited when winding variable-diameter pipes, products with uneven surfaces, and special-shaped products, and curing and demolding are also extremely difficult. Although there are metal molds that can achieve variable diameters, their complex structure and unstable function make them of no practical value in actual production.

[0004] Patent number CN2915475 discloses a variable-diameter mold for producing fiberglass reinforced plastic (FRP) pipes. The cylinder features an axially defined slit on its sidewalls, which mate with the sidewalls of long strips. The strips' outer surfaces are arc-shaped, with the same curvature as the cylinder's outer surface. The inner ends of the strips are connected to a drive device mounted within the cylinder. The cylinder is manufactured to the nominal diameter of the FRP pipe and the desired FRP pipe is wound around it. After the FRP pipe solidifies, a hydraulic control device retracts the piston rods of multiple cylinders through pipelines, driving the strips inward. This loosens the fit between the cylinder and the FRP pipe, allowing the pipe to separate from the cylinder. The variable diameter mold has many structural components, complex connection relationships, high production and manufacturing costs, and poor economic benefits. Secondly, the demolding process requires multiple sets of power coordination, which is unstable to use, has a high equipment failure rate, and high maintenance costs. Furthermore, the rigid metal core mold cannot complete the winding of variable diameter pipes and special-shaped pipes, and the heat loss during the curing heating process is still large, making demolding difficult. Summary of the Invention

[0005] The purpose of the present invention is to provide a variable diameter mold that can adapt to the fiberglass winding of variable diameter special-shaped components, improve the demoulding efficiency through flexible deformation, and has a simple and compact structure and is easy to process and manufacture. Its rubber material bladder composite structure significantly reduces heat conduction and improves the utilization rate of curing heat energy.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A variable diameter mold for fiberglass winding, characterized in that it includes a core shaft and an elastic bladder sleeved on the outside of the core shaft; wherein the elastic bladder includes seals at both ends and a plurality of annular fins or spiral fins arranged on the inner surface of the elastic bladder, the annular fins are arranged and sleeved on the outside of the core shaft and their radial directions are obliquely intersected with the axial directions of the core shaft. After the elastic bladder is filled with a medium, the inner edges of the annular fins clamp the core shaft and the outer edges support the elastic bladder to form a variable diameter core mold for fiberglass winding.

[0008] The additional technical features of the above-mentioned variable diameter mold for fiberglass winding also include:

[0009] The core shaft is a hollow tube with at least one through hole on its surface for communicating with the elastic fetal sac. The roots of the annular fins are provided with one or more through holes. The core shaft has a medium pipe connected to the through hole, and the medium pipe is connected to the pump body.

[0010] The through holes are connected to the inner surface of the elastic fetal sac, and the through holes of adjacent annular fins are aligned along the axial direction of the core shaft to form a receiving space for the wrinkled outer surface of the elastic fetal sac;

[0011] A one-way valve for overpressure relief is provided on the through hole, and a pressure sensor is provided on the through hole. The pressure sensor and the pump body are both electrically connected to a PLC controller for automatic charging and discharging of the medium;

[0012] The elastic foetal sac is filled with gas, and the air pressure is within the range of 0.5 MPa ± 10%;

[0013] ——The core shaft is made of metal, and the elastic fetal sac is made of rubber composite material.

[0014] Compared with the prior art, the variable diameter mold for FRP winding provided by the present invention comprises a core shaft and an elastic bladder sleeved on the outside thereof, and the inner surface of the elastic bladder has annular fins arranged and sleeved on the outside of the core shaft and obliquely intersecting with the radial direction and the axial direction of the core shaft, that is, after the elastic bladder is filled with a medium, the inner edge of the annular fins clamps the core shaft and the outer edge supports the elastic bladder to form a mold lining for FRP winding, which has the following advantages: first, the outer diameter of the winding mold is changed by filling and discharging the medium in the elastic bladder, which is convenient for smoothly withdrawing the finished product from the mold after heating and curing, and the annular fins in the elastic bladder play a supporting role, the root (outer edge) of the annular fin is connected to the inner surface of the elastic bladder, and the end (inner edge) is clamped on the core shaft, which can transmit sufficient torque when the mold is winding to prevent the elastic bladder and the core shaft from sliding relative to each other, and the winding is fast and stable; second, since there are annular fins arranged and sleeved between the elastic bladder and the core shaft The fins, that is, the elastic fetal sac, are expanded with the axis of the core shaft as the center when the medium is filled, forming a strong support for the elastic fetal sac. When the curing is completed and the mold is removed, the medium is discharged, and the annular fins are contracted with the axis of the core shaft as the center, so that the width of the elastic fetal sac is uniformly reduced; thirdly, the width of the arranged and set annular fins can be adaptively adjusted according to the specific specifications of the wound product, so that the outer surface of the elastic fetal sac forms a winding core mold of various forms. The mold can be used to wind fiberglass products with variable diameters, concave and convex fluctuations, and various special-shaped structures, which broadens the scope of use of the mold; fourthly, the variable diameter mold is a composite structure composed of a central core shaft and an elastic fetal sac mounted on the outside. The elastic fetal sac can be inflated and deformed, and is generally made of rubber composite materials with slow heat conduction speed. After the elastic fetal sac is filled with gas or pressure oil, it also has an insulating function, that is, in the curing process, the thermal energy utilization rate is good, the curing efficiency and cost are significantly reduced, and it has outstanding economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a variable diameter die for fiberglass winding according to the present invention;

[0016] Figure 2 It is a cross-sectional schematic diagram of the elastic fetal sac of the variable diameter mold. DETAILED DESCRIPTION

[0017] The structure and working principle of a variable diameter die for fiberglass winding provided by the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] See also Figure 1, which is a schematic diagram of the structure of a variable diameter mold for FRP winding provided by the present invention. The structure of the novel variable diameter mold includes a core shaft 1 and an elastic bladder 2 mounted on the outside thereof; the elastic bladder 2 includes plugs 21 at both ends and a plurality of annular fins 22 or spiral fins disposed on the inner surface of the elastic bladder 2. The spiral fins or annular fins 22 are arranged and mounted on the outside of the core shaft 1, with their radial direction obliquely intersecting with the axial direction of the core shaft 1. After the elastic bladder 2 is filled with a medium, the inner edges of the annular fins 22 clamp the core shaft 1, while their outer edges support the elastic bladder 2, forming a variable diameter core mold for FRP winding.

[0019] Its working principle is as follows: the core shaft 1 of the mold is assembled with the winding equipment, and an elastic bladder 2 is mounted on the outside of the core shaft 1. The inner surface of the elastic bladder 2 has multiple annular fins 22. The annular fins 22 are arranged and mounted on the outside of the core shaft 1 and are obliquely intersected with the radial direction and the axial direction of the core shaft 1. That is, the elastic bladder 2 is filled with a medium (generally gas, pressure oil, etc.), and the annular fins 22 expand and contract with the axial direction as the center to achieve the change of the diameter of the entire core mold, which is convenient for demolding. In addition, the width of the annular fins 22 can be changed according to the shape of the wound product to achieve winding of variable diameter, bending and special-shaped structures.

[0020] In the structure constituting the above-mentioned variable diameter die,

[0021] ——In order to improve the inflation and deflation efficiency of the elastic fetal sac 2 and achieve the requirement of rapid deformation, the core shaft 1 is a hollow tube with at least one through hole 11 provided on its surface for communicating with the elastic fetal sac 2. The core shaft 1 has a medium pipe 12 connected to the through hole 11. The medium pipe 12 is connected to the pump body 5. The elastic fetal sac 2 is quickly inflated and deflated through the through hole 11, such as by air or liquid. Figure 2 As shown, preferably, one or more through holes 23 are provided at the root (outer edge) of the annular fin 22, so as to achieve consistency of the overall pressure of the elastic bladder 2, uniform internal pressure, stable and balanced changes, so that the outer surface of the elastic bladder 2 always remains regular, and it is convenient to form a high-quality wrapped product;

[0022] Furthermore, the through holes 23 are connected to the inner surface of the elastic bladder 2. The through holes 23 of adjacent annular fins 22 are aligned along the axial direction of the core shaft 1, forming a space for accommodating the wrinkled outer surface of the elastic bladder 2. A plurality of through holes 23 are located at the root of each annular fin 22 and are evenly distributed along the circumference. That is, when viewed axially, all the through holes 23 are connected to the elastic bladder 2 to form an empty slot frame. After the elastic bladder 2 releases the medium, wrinkles are formed at the through holes 23 and the through holes 23 are recessed into the through holes 23, facilitating the rapid exit of the core shaft 1 and the elastic bladder 2 from the winding member.

[0023] As a preferred embodiment, a one-way valve 3 for overpressure relief is provided on the through hole 11. When the pressure of the filling medium inside the elastic foetal sac 2 is too high or exceeds a preset value during the heating and curing process, the one-way valve 3 opens the through hole 11 to release the overpressure. A pressure sensor 4 is provided on the through hole 11. The pressure sensor 4 and the pump body 5 connected to the medium pipeline 12 are both electrically connected to the PLC controller 6 for automatic pressurization. This ensures that the internal pressure of the elastic foetal sac 2 is always in an intelligent monitoring state, with relief in the event of overpressure and automatic filling of the medium in the event of underpressure, thereby ensuring that the elastic foetal sac 2 always maintains a stable appearance and structural strength.

[0024] ——In one embodiment, the elastic bladder 2 is filled with gas, and the air pressure is within the range of 0.5Mpa±10%, preferably maintained at 0.5Mpa, which is more in line with the safety requirements of fiberglass winding and forms a stable winding core mold. Furthermore, the core shaft 1 is made of metal, such as steel, stainless steel and other materials, and the elastic bladder 2 is made of rubber composite material. Rubber composite material refers to a composite material with cord (polyester, nylon, rayon, steel wire, etc.) as the reinforcing phase and rubber as the matrix. It has excellent viscoelasticity, large deformation, high modulus ratio (up to 3 to 4 orders of magnitude) and other properties, and has both flexibility and mechanical strength. The composite structure variable diameter mold composed of the elastic bladder 2 and the core shaft 1 has the advantages of light weight, flexible winding, and easy use and maintenance.

Claims

1. A variable diameter die for fiberglass winding, characterized by: It includes a core shaft and an elastic fetal sac sleeved on the outside of the core shaft; wherein, The elastic fetal sac includes plugs at both ends and a plurality of annular fins or spiral fins arranged on the inner surface of the elastic fetal sac. The annular fins are arranged and sleeved outside the core shaft, and their radial directions are obliquely intersected with the axial directions of the core shaft. After the elastic fetal sac is filled with a medium, the inner edges of the annular fins clamp the core shaft and the outer edges support the elastic fetal sac to form a variable diameter core mold for winding the fiberglass reinforced plastic. The core shaft is made of metal, and the elastic fetal sac is made of a rubber composite material; wherein, the core shaft is a hollow tube, and at least one through hole is provided on its surface for connecting to the elastic fetal sac, and one or more through holes are provided at the root of the annular fin, and a medium pipe connected to the through hole is provided in the core shaft, and the medium pipe is connected to the pump body.

2. The variable diameter mold for fiberglass winding according to claim 1, characterized in that: The through holes are connected to the inner surface of the elastic fetal sac, and the through holes of adjacent annular fins are aligned along the axial direction of the core shaft to form an accommodating space for the wrinkled outer surface of the elastic fetal sac.

3. The variable diameter mold for fiberglass winding according to claim 1, characterized in that In: A one-way valve for overpressure relief is provided on the through hole, and a pressure sensor is provided on the through hole. The pressure sensor and the pump body are both electrically connected to a PLC controller for automatic charging and discharging of the medium.

4. A variable diameter die for fiberglass winding according to claim 1 or 3, characterized in that The feature is that the elastic foetal sac is filled with gas, and the air pressure is maintained within the range of 0.5 MPa ± 10%.

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