CN-115742355-B - Die for NOL ring preparation and forming method

Abstract

The invention discloses a die for NOL ring preparation and a forming method, wherein a clamp is designed on the surface of a split cylinder core die, the axial width of a sample is adjusted, two different NOL ring preparation methods of a single ring winding method and a cylinder ring cutting method can be adopted according to requirements, the die is compact in design, 3 NOL rings can be simultaneously wound for a single time after a yarn splitting comb of a winding machine is refitted, the efficiency is improved by 2 times, after winding is finished, a vacuum bag can be manufactured on the surface of a smooth core die after the clamp is removed, so that partial dry prepreg samples can be cured under bag pressure or autoclave pressure, and the interlayer shear strength of the samples is improved by 70% under external forming pressure compared with that of samples without external compression.

Inventors

• LUO RUI
• CHEN DONG
• ZHU HAORAN

Assignees

• 南京晨光集团有限责任公司

Dates

Publication Date

20260505

Application Date

20221122

Claims (8)

1. 1. The die for NOL ring preparation is characterized by comprising a mandrel, a front cover plate, a rear cover plate, a cylindrical mandrel, a clamp, a yarn dividing comb and a pressure equalizing plate; two discs are symmetrically protruded on the mandrel and used for supporting the cylindrical mandrel on the mandrel, and the outer diameter of each disc is equal to the inner diameter of the cylindrical mandrel; The cylindrical core mould adopts a multi-petal structure; the front cover plate and the rear cover plate are respectively arranged at two sides of the cylindrical core mould, so that boundary limitation is provided for cylindrical winding, and the circumferential dislocation and axial dislocation of the cylindrical core mould are limited; the front cover plate and the rear cover plate respectively extend inwards, and the inner wall of the extension section is matched with the outer diameter of the cylindrical core mould; The clamp hoop is tightly hooped on the surface of the cylindrical core mould, and the inner diameter of the clamp hoop is equal to the outer diameter of the cylindrical core mould; when the single ring is wound, the assembly space between the adjacent hoops is NOL ring sample width, and when the cylinder is wound, the assembly space between the adjacent hoops is self-defined cylinder width; The mandrel is L in length, the discs are b d in width, the distance between two discs on the mandrel is L d =L-2b d , the lengths of the inward extension of the front cover plate and the rear cover plate are L p , and the L=2l p +（n-1）b h +nb nol is met, wherein n is the number of single-ring samples formed, b h is the width of a clamp, b nol is the assembly distance between adjacent clamps, and the positions of the clamps are adjustable; The yarn dividing comb is provided with a plurality of rubber rolls, the space between the rubber rolls is adjustable, every two rubber rolls form a group, the space L r1 =b c +D r between the adjacent two rubber roll axes in each group is the space L r2 =b r +D r between the adjacent two rubber roll axes between the groups, wherein b c is the yarn width, D r is the rubber roll diameter, and b r is the space between the adjacent two rubber rolls between different groups; The equalizing plate is equal in width to the sample, and is fixed on the surface of the sample when being used for winding the dry prepreg so as to fix and cure the sample.
2. 2. The mold for NOL ring production according to claim 1, wherein the spacing between adjacent two rubber rolls between the sets satisfies 2D r +b c +b r =b h +b nol .
3. 3. The mold for the preparation of the NOL ring according to claim 1, wherein the cylindrical core mold adopts a three-flap structure.
4. 4. A mold for NOL ring production according to claim 3, wherein the three segments of the cylindrical mandrel have uneven arc lengths, and the angle between the normals of the two side surfaces of the smaller one segment mandrel is an obtuse angle.
5. 5. The mold for NOL ring production according to claim 4, wherein the outer arc length of the other two core mold segments is lc 2 , satisfying the outer arc length of lc 1 +2lc 2 =πD c ,lc 1 being a smaller one core mold segment, and D c being the outer diameter of the cylindrical core mold.
6. 6. A molding method for preparing a sample of a non-l ring, characterized in that the mold for non-l ring preparation according to any of claims 3 to 5 is used, comprising the steps of: Step 1, after assembling a mandrel, a front cover plate, a rear cover plate and a three-piece cylinder core module together, adjusting the number and the interval of the clamping bands, and locking; step 2, programming a processing program on a winding machine, and defining the thickness of a sample; Step 3, for a single ring winding method, a yarn dividing comb at the outlet of a yarn box of a winding machine and at the tail end of a yarn guide nozzle is replaced before preparation, the distances L r1 and L r2 between the axes of two rubber rolls in the same group and two adjacent rubber rolls in different groups are adjusted according to the actual yarn width b c , fiber impregnating resin or prepreg is adopted for circumferential winding, n t single-ring tensile samples with the thickness of h t and n s single-ring layer shear samples with the thickness of h s are prepared according to requirements between n-1 clamps with the distance of b nol , n t +n s = n, n t ' continuous circular winding is carried out between two cover plates in n ' -1 adjacent clamp ranges in n ' sections according to the cylinder ring cutting method, n t ' single-time cylindrical tensile samples with the thickness of h t and n s ' cylindrical layer shear with the thickness of h s are prepared, and n t ' +n s ' =n ' ; step 4, after winding is completed, the wet winding sample can directly enter an oven for curing, part of the dry prepreg winding sample needs to be dismantled and a split equalizing plate is placed on the surface of the sample to obtain a smooth workpiece surface, sealing rubber strips are placed on two sides of the sample to prevent excessive overflow of resin, then an isolating film and an airfelt are sequentially placed, vacuum bags are fixed at two ends of a mandrel through the sealing rubber strips, and finally the dry prepreg winding sample enters the oven for vacuum pumping bag for curing or enters an autoclave for curing; And 5, after the solidification is finished, removing the auxiliary material, the mandrel and the front cover plate and the rear cover plate, taking out the cylindrical mandrel, and thus demoulding all the samples at one time.
7. 7. The molding method for preparing a NOL ring sample as claimed in claim 6, wherein the thickness of the sample is controlled by the number of windings, and the thickness t ply of the winding monolayer is calculated by the following formula: ; wherein Y is the linear density of the fiber bundles, V f is the volume fraction of the fibers, and is the density of the fibers; The number of winding turns c t of the tensile test piece and the number of winding turns c s of the layer shear test piece are calculated by the following formula: ; where h t is the tensile specimen thickness and h s is the layer shear specimen thickness.
8. 8. The molding method for preparing NOL ring samples according to claim 7, wherein the single ring winding samples do not need to be widened, the cylindrical winding samples need to be widened to b nol , and then the samples are subjected to test after deburring and layer shearing.

Description

Die for NOL ring preparation and forming method Technical Field The invention belongs to the field of composite material fiber winding forming, and particularly relates to a die for NOL ring preparation and a forming method. Background The composite material fiber winding forming process is widely applied in civil and national defense fields due to the characteristics of low cost, stable quality and the like, and becomes an ideal process forming method for fiber reinforced composite material rotors, pressure vessels, solid rocket engine shells and the like. For winding processes, the tensile property and the shearing property of NOL ring samples are often used as evaluation standards, the process rationality is verified, and the forming modes are divided into a single ring winding method and a cylindrical ring cutting method. At present, a single-ring winding method is mostly adopted to ensure the fiber continuity of the sample, avoid damaging the performance of the sample due to mechanical processing, and a cylinder ring cutting method can ensure the uniform winding of the inner material of the NOL ring and avoid influencing the performance of the sample due to sliding wires at two sides in the winding process. Winding processes for preparing NOL rings are classified into wet processes and dry processes, and for NOL rings wound with a part of dry prepregs, external forming pressure is required to be provided during curing so as to fully compact the layers. However, most existing dies are single-purpose single-ring dies, NOL cylinders cannot be formed, the die structure is complex, only 1 NOL ring can be wound at a time, external pressure conditions are not provided, winding tension is used as curing forming pressure, and interlayer quality of certain dry NOL rings is difficult to ensure. In order to prepare NOL ring samples meeting the requirements, a single ring winding die and a forming tool are provided for related units. The diameter of the sample is ensured by a die, the width is ensured by a left baffle plate and a right baffle plate or a machine tool, and the outer diameter is ensured by winding process control and polishing in the thickness direction. According to the scheme, the problem that NOL ring samples are prepared by a single-ring winding method is primarily solved, in actual operation, a die does not have universality, only single-ring samples can be prepared, when the influence of sliding wires on the uniformity of internal materials is large, the samples cannot be prepared by a cylindrical ring cutting method, when the single-ring winding is carried out, only 1 NOL ring can be wound at a time, the forming efficiency is low, and when part of prepreg dry-winding samples are solidified, effective external pressure cannot be provided, and the interlayer shearing performance is low. Patent number CN 204894497U, a winding mold assembly for making a NOL ring of a resin-based fiber composite material, designs a NOL ring winding mold assembly, and a plurality of single ring winding molds can be sleeved on a mandrel to realize winding and forming of a plurality of NOL rings. But the segmented mold characteristics determine that the mold cannot produce a NOL cylinder, only 1 NOL ring can be wound at a time, and no external pressure can be applied during curing. Patent number CN 114074434A, "a winding device for manufacturing NOL ring of composite material," developed a single winding device for NOL ring, which can conveniently and rapidly prepare NOL ring, and simultaneously can control winding speed, winding tension, glue content, yarn spreading width and other technological parameters. However, only one NOL single ring can be prepared at a time, and the conditions for curing the vacuum bag are not met. Disclosure of Invention The invention aims to provide a die and a forming method for NOL ring preparation, which are used for solving the problems of poor universality, low forming efficiency and inapplicability to bag pressure and autoclave curing of the existing NOL ring winding tool. The technical solution for realizing the purpose of the invention is as follows: A die for NOL ring preparation comprises a mandrel, a front cover plate, a rear cover plate, a cylindrical mandrel, a clamp, a yarn dividing comb and a pressure equalizing plate; two discs are symmetrically protruded on the mandrel and used for supporting the cylindrical mandrel on the mandrel, and the outer diameter of each disc is equal to the inner diameter of the cylindrical mandrel; The cylindrical core mould adopts a multi-petal structure; the front cover plate and the rear cover plate are respectively arranged at two sides of the cylindrical core mould, so that boundary limitation is provided for cylindrical winding, and the circumferential dislocation and axial dislocation of the cylindrical core mould are limited; the front cover plate and the rear cover plate respectively extend inwards, and the inner wall of the extension sec