Yarn spreading uniformity detection method for carbon fiber prepreg

Abstract

The invention discloses a yarn spreading uniformity detection method for a carbon fiber prepreg, which scientifically and reliably detects the yarn spreading uniformity of the carbon fiber prepreg in a set and selected piece to be detected, so that theoretical support is provided for subsequent quality control and performance evaluation of a carbon fiber composite material. The carbon fiber model of the carbon fiber prepreg is obtained in advance, a to-be-detected piece with the unit area of L * W is taken down from the carbon fiber prepreg, then three parts are cut along the width line of the to-be-detected piece with the unit area, each part is provided with N sample strips with the same size, the length of each sample strip is L1, and the width of each sample strip is W1; the 3N splines are subjected to carbon fiber content detection, the numerical values of the carbon fiber content are recorded, the maximum value and the minimum value of the carbon fiber content are compared with the carbon fiber standard value obtained through sample size calculation, the carbon fiber prepreg yarn is qualified when the error of the carbon fiber content is within + / -3.0%, and the carbon fiber prepreg yarn is unqualified when the error of the carbon fiber content is not within + / -3.0%.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber prepreg detection, in particular to a method for detecting yarn spreading uniformity of carbon fiber prepreg. Background Art

[0002] Carbon fiber prepreg, as a key semi-finished material formed by impregnating carbon fiber tows with resin, has a wide range of applications in the field of composite material manufacturing. The uniformity of the yarn spread of carbon fiber prepreg plays a vital role in the performance of the final composite product, especially for ultra-thin and low-warpage carbon fiber composite products. The importance of yarn spread uniformity is even more prominent. However, in the current technical field, there is a lack of efficient and accurate methods to accurately detect the uniformity of the yarn spread of carbon fiber prepreg, which brings great challenges to the quality control and performance evaluation of carbon fiber composites. Summary of the invention

[0003] In view of the above problems, the present invention provides a method for detecting the yarn spreading uniformity of carbon fiber prepreg, which scientifically and reliably performs the yarn spreading uniformity detection of the carbon fiber prepreg in the selected test piece, thereby providing theoretical support for the subsequent quality control and performance evaluation of carbon fiber composite materials.

[0004] A method for detecting the uniformity of yarn spreading of carbon fiber prepreg, characterized in that: the carbon fiber model of the carbon fiber prepreg is known in advance, a piece to be tested with a unit area of ​​L×W is taken from the carbon fiber prepreg, and then three parts are intercepted along the width of the piece to be tested with a unit area, each part has N splines of the same size, and each spline has a length of L1 and a width of W1, and the carbon fiber content of the 3N splines is detected and the carbon fiber content value is recorded, and the maximum and minimum values ​​of the carbon fiber content are compared with the carbon fiber standard value obtained by calculating the spline size. The carbon fiber prepreg is qualified if the carbon fiber content is within an error of ±3.0%, otherwise it is unqualified.

[0005] It is further characterized by:

[0006] The value of W in the unit area is selected as 1000 mm, and the value of L is greater than 1000 mm;

[0007] The length L1 of each spline is 1000 mm to facilitate the determination of the standard value;

[0008] The width of the unit area of ​​the piece to be tested is measured by cutting the sample strips at the two sides and the middle three positions along the line, so that the sampling coverage of the sample strip is wide;

[0009] The N splines intercepted from each part are discontinuous and have intervals in the width direction, and each spline does not select the front and rear end edges and the two side edges to ensure that the size of the spline meets the standards of length L1 and width W1;

[0010] According to the model of carbon fiber and the shrinkage of carbon fiber during the prepreg process, the standard value of carbon fiber content of carbon fiber prepreg with length L1 and width W1 is calculated;

[0011] Preferably, the maximum and minimum values ​​of the carbon fiber content are compared with the carbon fiber standard value obtained by calculating the spline size, and the carbon fiber prepreg yarn is qualified if the carbon fiber content is within an error of ±2.0%;

[0012] Preferably, the value of N is 3 to 8;

[0013] The sample strips are placed in different independent containers, and the water bath extraction and distillation method is used to accurately weigh the sample strip carbon fiber mass and thus obtain the carbon fiber content, providing key data for determining the uniformity of the yarn.

[0014] After each sample strip is numbered, the obtained carbon fiber content data is entered into the database and pointed to the material number of the carbon fiber prepreg being tested, so as to establish the source of raw materials for subsequent testing based on the quality of the finished product.

[0015] After adopting the present invention, the standard carbon fiber content value of a spline with a length of L1×width W1 is pre-calculated according to the carbon fiber model of the carbon fiber prepreg and the actual situation of the carbon fiber prepreg, and then three parts are cut on the test piece with a unit area of ​​L×W, and N splines with the same size in each part are cut, and the length of each spline is L1×width W1, and the spline area covers a wide range. The 3N splines are respectively tested for carbon fiber content and the carbon fiber content values ​​are recorded, and the maximum and minimum values ​​of the carbon fiber content are compared with the carbon fiber standard value obtained by calculating the spline size. The carbon fiber prepreg is qualified if the carbon fiber content is within an error of ±3.0%, otherwise it is unqualified. The uniformity detection of the yarn spreading of the carbon fiber prepreg in the selected test piece is set scientifically and reliably, thereby providing theoretical support for subsequent quality control and performance evaluation of carbon fiber composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the sampling strip of the method of the present invention. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0019] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0020] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0021] A method for detecting the uniformity of the yarn spread of carbon fiber prepreg, see Figure 1 : Know the carbon fiber model of the carbon fiber prepreg in advance, take a test piece with a unit area of ​​L×W on the carbon fiber prepreg, then cut three parts along the width of the unit area of ​​the test piece, each part has N splines of the same size, each spline has a length of L1 and a width of W1, and perform carbon fiber content detection on the 3N splines and record the carbon fiber content value, compare the maximum and minimum carbon fiber content with the carbon fiber standard value obtained by calculating the spline size, and the carbon fiber prepreg is qualified if the carbon fiber content is within an error of ±3.0%, otherwise it is unqualified carbon fiber prepreg.

[0022] In a specific embodiment, T700 / 12k carbon fiber is used as raw material to prepare UD100 carbon fiber prepreg, and its carbon fiber shrinkage rate is 20%, which includes the following steps:

[0023] S1. Cut the prepreg to obtain a piece to be tested with a unit area of ​​L×W, where L is a value greater than 1000 mm, and W is equal to 1000 mm;

[0024] S2, select the length L1 of the spline as 1000mm, calculate the spline width W1 according to the model of carbon fiber and the shrinkage of carbon fiber in the prepreg process, and obtain the standard value of carbon fiber content of carbon fiber prepreg with length L1 and width W1. For the convenience of calculation, first obtain the weight value of a single carbon fiber with a length of 1000mm in a non-shrinking state as the standard value, and then calculate the spline width W1;

[0025] The specific calculation process is as follows: the specification of 12K carbon fiber is 800tex, and the weight of a single bundle of carbon fiber (the weight of one meter) is 0.8g (800g / 1000m), that is, the standard value is 0.8g. There are 125 bundles of carbon fiber filaments in 100g of carbon fiber prepreg. In the prepreg with a width of W=1000mm, the theoretical yarn spreading width of each filament bundle is 8mm (1000mm / 125 bundles); considering the yarn spreading effect of the carbon fiber bundle, the sample width W1 can be calculated to be 6.4mm (8mm*80%) by shrinking 20% ​​on the basis of 8mm, and then the sample size is determined to be L1×W1=1000MM×6.4mm;

[0026] S3, precise cutting, according to the calculated spline width, use a cutting machine to evenly cut out 15 splines (N value is 5), to ensure the consistency and accuracy of the spline size, the cutting size of each spline is 1000mm*6.4mm spline;

[0027] The splines are cut from the two sides and the middle three parts along the width of the piece to be tested. The five splines cut from each part are discontinuous and have intervals in the width direction. Each spline does not select the front and rear end edges and the two side edges to ensure the spline size.

[0028] S4. Carbon fiber content determination: the sample strips are placed in different independent containers, and the water bath extraction and distillation method is used to accurately weigh the carbon fiber mass of the sample strips, thereby obtaining the carbon fiber content, which provides key data for the determination of yarn uniformity;

[0029] S5. After each spline is numbered, the obtained carbon fiber content data is entered into the database and pointed to the material number of the tested carbon fiber prepreg, so as to establish the source of raw materials for subsequent testing according to the quality of the finished product. The calculation module automatically compares the maximum and minimum carbon fiber content with the carbon fiber standard value obtained by calculating the spline size. The carbon fiber content within the error of ±2.0% is qualified carbon fiber prepreg, otherwise it is unqualified carbon fiber prepreg.

[0030] The principle is as follows: according to the carbon fiber model of the carbon fiber prepreg and the actual situation of the carbon fiber prepreg, the standard carbon fiber content value of the spline with a length of L1×width W1 is calculated in advance, and then three parts are cut on the test piece with a unit area of ​​L×W, and N splines of the same size are each part. The length of each spline is L1×width W1, and the spline covers a wide area. The 3N splines are respectively tested for carbon fiber content and the carbon fiber content values ​​are recorded. The maximum and minimum values ​​of the carbon fiber content are compared with the carbon fiber standard value obtained by calculating the spline size. The carbon fiber prepreg is qualified if the carbon fiber content is within an error of ±3.0%, otherwise it is unqualified. The uniformity detection of the yarn spread of the carbon fiber prepreg in the selected test piece is set scientifically and reliably, thereby providing theoretical support for the subsequent quality control and performance evaluation of carbon fiber composite materials.

[0031] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0032] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for detecting the uniformity of yarn spreading of carbon fiber prepreg, characterized in that: The carbon fiber model of the carbon fiber prepreg is known in advance, and a test piece with a unit area of ​​L×W is taken from the carbon fiber prepreg. Then, three parts are cut along the width of the unit area of ​​the test piece, and N splines of the same size are taken at each part. The length of each spline is L1 and the width is W1. The carbon fiber content of the 3N splines is tested and the carbon fiber content value is recorded. The maximum and minimum values ​​of the carbon fiber content are compared with the carbon fiber standard value obtained by calculating the spline size. The carbon fiber prepreg yarn is qualified if the carbon fiber content is within the error of ±3.0%, otherwise it is unqualified.

2. A method for detecting yarn spreading uniformity of carbon fiber prepreg according to claim 1, characterized in that: The value of W per unit area is selected as 1000 mm, and the value of L is greater than 1000 mm.

3. A method for detecting yarn spreading uniformity of carbon fiber prepreg according to claim 2, characterized in that: The length L1 of each spline is 1000 mm.

4. The method for detecting the uniformity of yarn spreading of carbon fiber prepreg according to claim 1, characterized in that: Sample strips are cut from the two sides and three locations in the middle along the width of the unit area of ​​the test piece.

5. A method for detecting the uniformity of yarn spreading of carbon fiber prepreg according to claim 4, characterized in that: The N splines intercepted from each part are discontinuous with each other and are spaced apart in the width direction, and each spline does not select the front and rear end edges and the two side edge areas.

6. The method for detecting the uniformity of yarn spreading of carbon fiber prepreg according to claim 1, characterized in that: According to the model of carbon fiber and the shrinkage of carbon fiber during the prepreg process, the standard value of carbon fiber content of carbon fiber prepreg with length L1 and width W1 is calculated.

7. The method for detecting the uniformity of yarn spreading of carbon fiber prepreg according to claim 1, characterized in that: The maximum and minimum values ​​of the carbon fiber content are compared with the carbon fiber standard value obtained by calculating the spline size. The carbon fiber prepreg yarn is qualified if the carbon fiber content is within the error of ±2.0%.

8. A method for detecting yarn spreading uniformity of carbon fiber prepreg according to claim 1 or 4, characterized in that: The value of N ranges from 3 to 8.

9. The method for detecting the uniformity of yarn spreading of carbon fiber prepreg according to claim 1, characterized in that: The specimens were placed in different independent containers, and the carbon fiber mass of the specimens was accurately weighed to obtain the carbon fiber content using a water bath extraction distillation method.

10. A method for detecting yarn spreading uniformity of carbon fiber prepreg according to claim 1, characterized in that: After each sample strip is numbered, the obtained carbon fiber content data is entered into the database and pointed to the material number of the carbon fiber prepreg being tested, so as to establish the source of raw materials for subsequent testing based on the quality of the finished product.

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